1.
Directions: questions 1-5
Match each antihypertensive drug with its appropriate mechanism of action (each lettered option
can be selected once, more than once, or not at all):
Nitric oxide is the active metabolite
Correct Answer
M. Nitroprusside
Explanation
Nitroprusside is the correct answer because it is a potent vasodilator that works by releasing nitric oxide. Nitric oxide relaxes the smooth muscle in blood vessels, leading to vasodilation and a decrease in blood pressure. This mechanism of action makes nitroprusside an effective antihypertensive drug.
2.
Directions: questions 1-5
Match each antihypertensive drug with its appropriate mechanism of action (each lettered option
can be selected once, more than once, or not at all):
Activation of D1 receptors
Correct Answer
E. Fenoldopam
Explanation
Fenoldopam is the correct answer because it activates D1 receptors. The other drugs listed do not have this mechanism of action.
3.
Directions: questions 1-5
Match each antihypertensive drug with its appropriate mechanism of action (each lettered option
can be selected once, more than once, or not at all):
Blockade of AT1 receptors
Correct Answer
J. Losartan
Explanation
Losartan is an angiotensin II receptor antagonist, which means it blocks the AT1 receptors. By blocking these receptors, losartan prevents the binding of angiotensin II to its receptors, leading to vasodilation and a decrease in blood pressure. This mechanism of action makes losartan an effective antihypertensive drug.
4.
Directions: questions 1-5
Match each antihypertensive drug with its appropriate mechanism of action (each lettered option
can be selected once, more than once, or not at all):
Potassium channel opening in smooth muscle cells
Correct Answer
C. Diazoxide
Explanation
Diazoxide is a potassium channel opener, which means it works by opening potassium channels in smooth muscle cells. This leads to hyperpolarization of the cells, preventing calcium influx and ultimately causing relaxation of the smooth muscle. This mechanism of action helps to lower blood pressure, making diazoxide an effective antihypertensive drug.
5.
Directions: questions 1-5
Match each antihypertensive drug with its appropriate mechanism of action (each lettered option
can be selected once, more than once, or not at all):
Competitive inhibition of renin
Correct Answer
A. Aliskiren
Explanation
Aliskiren is a drug that competitively inhibits renin. Renin is an enzyme that plays a role in the production of angiotensin II, a hormone that causes vasoconstriction and increases blood pressure. By inhibiting renin, Aliskiren reduces the production of angiotensin II, leading to vasodilation and a decrease in blood pressure. This mechanism of action makes Aliskiren an effective antihypertensive drug.
6.
A 63-year-old man, recently diagnosed with stage 1 essential hypertension, started a
treatment with hydrochlorothiazide. After several weeks of treatment, the
antihypertensive action of the drug was most likely associated with which of the
following effects?
Correct Answer
C. Decreased peripHeral vascular resistance
Explanation
Learning objective: describe the main action leading to the antihypertensive effect of
thiazides.
Answer: C
The initial hypotensive effects of diuretics is associated with a reduction in plasma volume and
cardiac output. Peripheral vascular resistance is usually unaffected (or sometimes increased).
After 4-8 weeks of continuous therapy blood volume and cardiac output return towards normal
while peripheral vascular resistance decreases. Mechanisms of this decrease are probably
related to a depletion of body Na+ stores.
A) diuretics cause negligible postural hypotension since the baroreceptor reflex is not affected.
B)(see explanation above)
D) Thiazides tend to decrease, not increase, interstitial fluid volume.
E) Blood flow in any organ is related to perfusion pressure and vessel resistance. Perfusion
pressure in turn is mainly related to cardiac output. After several weeks of treatment with
diuretics, cardiac output is normal and therefore renal blood flow is either normal or increased,
not decreased.
7.
A 52-year-old man complained to his physician of acute pain at the base of his right
big toe. The man, who had been working as a painter for 15 years, was recently
diagnosed with essential hypertension and started an antihypertensive therapy one
month ago. A lab test showed a plasma uric acid level of 17 mg/dL. Which of the
following drugs might have caused the symptoms and signs of this patient?
Correct Answer
B. Hydrochlorothiazide
Explanation
Learning objective: describe the main adverse effects of thiazides.
Answer: B
The symptoms of the patient and the lab results indicate that he was most likely suffering from gout arthritis. Chronic treatment with thiazides may cause hyperuricemia and precipitate attacks
of gout in patients at risk. Hyperuricemia is likely due both to hypovolemia-induced increase of
uric acid reabsorption and to competition with urates for the organic acid transport system in the
proximal tubule.
Being a painter, the patient was already at risk of gout since a strong association exists
between the risk of gout and lead exposure through diet or occupations (painters, plumbers,
etc.)
D) Furosemide can cause hyperuricemia but the drug is rarely used as an antihypertensive.
A, C, E, F) These drugs do not cause hyperuricemia.
8.
A 65 year-old woman was found to have a blood pressure of 165/90 during a routine
visit. Past history of the patient was significant for a second-degree heart block and for
osteoporosis. One year ago she had suffered from a severe episode of angioedema.
Which of the following antihypertensive drugs would be most appropriate for this
patient?
Correct Answer
D. Hydrochlorothiazide
Explanation
Learning objective: identify the best antihypertensive drug in a patient with concomitant
diseases.
Answer: D
The patient has stage 2 essential hypertension and therefore an antihypertensive medication is
recommended, in addition to lifestyle modification. The patient is a good candidate for a
thiazide diuretic for several reasons. First these drugs are usually the most appropriate initial
choice in case of uncomplicated hypertension since they decrease morbidity and mortality.
Secondly the woman is suffering from osteoporosis and thiazides can cause retention of
calcium, a potentially beneficial effect. Moreover in this patient:
A) Ace-inhibitors are contraindicated because of the past episode of angioedema.
B, C) Beta-blockers and verapamil are contraindicated because of the heart block.
E) Minoxidil is never a drug of first choice for antihypertensive therapy.
9.
A 52-y/o woman suffering from HTN still had a blood pressure of 156/92 mm Hg after three months of therapy with hydrochlorotiazide and losartan. Her physician decided to add a third drug which acts by decreasing central sympathetic outflow.
Which of the following adverse effects might most likely occur after few days of therapy with the new drug?
Correct Answer
D. Pronounced sedation
Explanation
Learning objective: describe the main adverse effects of central sympathoplegic
antihypertensive drugs.
Answer: D
Sedation is a frequent, and sometimes pronounced, adverse effect of central sympathoplegic
antihypertensive drugs. (methyldopa and clonidine), likely related to the decreased adrenergic
transmission in the CNS.
A) Postural hypotension is an uncommon and usually slight adverse effect of methyldopa and
clonidine, since the basal central adrenergic tone is reduced but the baroreceptor reflex is still
operative.
B) Hemolytic, not megaloblastic, anemia occasionally occurs with methyldopa.
C) Methyldopa and clonidine tend to decrease the heart rate so palpitations are unlikely.
E) Methyldopa and clonidine frequently cause xerostomia, not sialorrhea. The mechanism of the
effect is still uncertain.
10.
A 65-year-old man with stage 2 essential hypertension, had been taking a thiazide
diuretic and losartan for three months but his blood pressure was still 160/95 mm Hg.
The physician decided to add a third drug and now his blood pressure was well
controlled. However, because the patient was experiencing daytime somnolence and dry
mouth, he decided to discontinue the prescribed medication. Twenty-four hour later he
exhibited restlessness, apprehension, tremor, sweating and tachycardia. Which of the
following drugs was most likely added to the patient regimen?
Correct Answer
E. Clonidine
Explanation
Learning objective: describe the symptoms of clonidine withdrawal.
Answer: E
The symptoms of the patient are most likely due to sudden clonidine withdrawal. Rebound
hypertension can occur (to levels above those present prior to treatment) but the syndrome can
appear in the absence of an overshot in blood pressure.
The symptoms and signs of the syndrome are associated with increased sympathetic discharge
(plasma levels of catecholamines are increased). The exact mechanism of the clonidine
withdrawn syndrome is not known but the rebound hypertension seems to be due to an up
regulation of alpha-1 Receptors.
A, B, C, D, F) All the other listed drugs do not cause the above mentioned syndrome.
11.
A 35-year-old woman in her 29th week of gestation was found to have a positive direct
Coombs’ test during a routine prenatal visit. Two months after she became pregnant, she
was diagnosed with stage 1 hypertension and started an antihypertensive therapy. Which
of the following drugs was she most likely taking?
Correct Answer
D. Methyldopa
Explanation
Learning objective: identify the antihypertensive drug that can most likely cause a positive
Coombs’ reaction.
Answer: D
Methyldopa is the most commonly used drug for chronic treatment of hypertension in pregnancy
in the US. This is mainly because of the largest experience with this drug during pregnancy.
Positive Coombs’ reaction occurs in up to 30% of patients treated for more than 6 months, but
hemolytic anemia occurs in 1-5% of cases only. This is a type II allergic drug reaction.
Apparently the drug is able to alter the RBC surface chemically, thereby uncovering an antigen
that induces and then reacts with an antibody, so causing cell lysis.
A, B, C, E, F) All these drugs do not cause positive Coombs’ test or hemolytic anemia.
12.
A 47-year-old man with a history of hypertension had been taking hydrochlorothiazide
for one month, but his blood pressure was not controlled despite adherence to
medication and nonpharmacologic measures. The patient was also trying to quit
smoking without success. The physician decided to add to the therapeutic regimen a
second drug that also could help the patient as an adjunct to a smoking cessation
program. Which of the following drug was most likely prescribed?
Correct Answer
D. Clonidine
Explanation
Learning objective: describe the therapeutic uses of clonidine. Answer: D Clonidine is the only antihypertensive that is also used in smoking cessation programs since it reduces anxiety, irritability and craving during tobacco withdrawal (it doubles the number who remain abstinent for six months of more). The mechanism of this action is uncertain but it seems related to the drug-induced decrease in central sympathetic outflow. This can mitigate many signs of sympathetic overactivity that are present during tobacco withdrawal. A, C, C, E) These drugs do not affect tobacco withdrawal.
13.
A 60-year-old man reported to his physician that he felt very dizzy and fainted upon standing up rapidly, after. The man, recently diagnosed with stage 1 essential hypertension and prostatic hyperplasia, started a drug treatment one week previously. Which of the following drugs most likely caused this adverse effect?
Correct Answer
D. Prazosin
Explanation
Learning objective: describe the main adverse effects of prazosin.
Answer: D
The drug taken by the patient was most likely prazosin, an antihypertensive agent sometimes
given to patients with concomitant prostatic hyperplasia, since it can also help urination by
relaxing the bladder internal sphincter Prazosin can cause marked postural hypotension and
syncope with the first dose (the so called "first-dose phenomenon"). This is likely due to the
blockade of alpha-1 receptors both in the arterioles (which impairs the reflex vasoconstriction)
and in the veins (which decreases venous return). The orthostatic effect attenuates over time.
The mechanism responsible for the development of such tolerance is not clear. Other
antihypertensive drugs that can cause syncope include labetalol, Ace-inhibitors, losartan and
nitroprusside.
A) Beta-blockers do not cause postural hypotension and syncope since they do not affect the
baroreceptor reflex.
B, C) Unlike drugs that dilate capacitance vessels, arteriolar vasodilators do not cause
significant postural hypotension and therefore the risk of fainting with these drug is negligible.
E) Central acting antiadrenergic agents usually do not cause significant postural hypotension
since they decrease the basal adrenergic tone, but the sympathetic nervous system can still be
activated by proper stimuli.
F) Fenoldopam is used only for hypertensive emergencies.
14.
A 61-year-old man suffering from hypertension had been taking hydrochlorothiazide and propranolol for two months but the therapy failed to completely control his blood pressure. The man was recently diagnosed with benign prostatic hyperplasia and experienced frequent nocturia. His physician decided to add a third drug which could also help the patient’s difficulty in urinating. A drug from which of the following drug classes was most likely prescribed?
Correct Answer
A. AlpHa-1 blockers
Explanation
Learning objective: describe the therapeutic uses of alpha-1 blockers.
Answer: A
Alpha-1 blockers (prazosin, terazosin, etc.) are used as antihypertensive drugs mainly in men
with prostatic hyperplasia since they relax the internal sphincter of the bladder and the prostate
capsule.
B, C, D, E, F) All these drugs do not have relaxant properties on the internal sphincter of the
bladder and prostate capsule.
15.
A 50-year-old woman complained to o her physician complaining of dizziness and
vertigo of three days duration. The woman, recently diagnosed with hypertension and
diastolic dysfunction, started a hypertensive therapy one week previously. Physical
examination showed blood pressure of 166/94 mm Hg while laying and of 140/83 mm Hg
while standing. Which of the following antihypertensive drugs was the patient most likely
taking?
Correct Answer
E. Labetalol
Explanation
Learning objective: identify the antihypertensive drug that can most likely cause postural
hypotension.
Answer: E
By blocking alpha-1 receptors labetalol affects the baroreceptor reflex which is responsible for
rapid, moment to moment adjustment in blood pressure, such as in transition from a reclining to
an upright posture. In fact the increased sympathetic outflow cannot induce the normal
vasoconstriction since alpha-1 receptors are blocked and therefore postural hypotension
results.
A) Beta-blockers in general cause negligible postural hypotension since the baroreceptor reflex
is not affected.
B) Clonidine acts centrally and reduces the sympathetic outflow. However the baroreceptor
reflex is only marginally affected and postural hypotension is slight.
C) Ace-inhibitors rarely cause postural hypotension. The reason is uncertain but could be due
to downward resetting of baroreceptors.
D) Thiazide diuretics in general cause negligible postural hypotension since the baroreceptor
reflex is not affected.
16.
A 38-year-old man was diagnosed with hypertension (156/95 mm Hg) during a routine
visit. Subsequent exams indicated he was affected by hypertrophic cardiomyopathy.
Which of the following antihypertensive drugs would be most appropriate for this
patient?
Correct Answer
E. Propranolol
Explanation
Learning objective: chose the appropriate antihypertensive drug for a patient suffering
from hypertrophic cardiomyopathy.
Answer: E
Beta blockers are drug of choice in hypertrophic cardiomyopathy since they increase the
duration of diastole, decrease left ventricular contractility and myocardial wall stress during
systole. In the present case they can also reduce the high blood pressure and are therefore the
most appropriate drugs for this patient.
A, B, C, D) These drugs do not improve, or even get worse the hypertrophic cardiomyopathy
and therefore are not suited for this patient.
F) The use of ACE inhibitors in hypertrophic cardiomyopathy is controversial. Some clinicians
think they have no role in the disease, others believes they are beneficial by limiting
hypertrophy.
17.
A 64-year-old man with a long history of hypertension presented to the hospital
complaining of the sudden onset of severe, sharp, diffuse chest pain which radiated to
his back. Physical examination revealed a pulse of 110 bpm and a blood pressure of
200/120 mm Hg. A CT scan showed a dissection of the arch of the aorta. An emergency
treatment was started IV. Which of the following pairs of drugs were most likely
administered?
Correct Answer
D. Nitroprusside and esmolol
Explanation
Learning objective: describe the use of antihypertensive drugs in aortic dissection.
Answer: D
Aortic dissection is a highly lethal disorder. Because mortality is highest in the hours after
dissection begins, drug therapy to lower the arterial pressure should be started as soon as
possible. Nitroprusside is given as a constant IV drip with the objective of reducing the blood
pressure to the lowest level compatible with adequate cerebral, coronary and renal perfusion.
Since nitroprusside used alone can cause reflex tachycardia, a beta-blocker is often used
concomitantly. An operative repair on an emergent basis usually follows the medical therapy.
A) Labetalol is used for acute aortic dissection, but the addition of prazosin is irrational since
labetalol itself is also an alpha-1 blocker.
B) Diazoxide is used in case of hypertensive emergency but the addition of hydralazine is
irrational since the drug can cause reflex tachycardia.
C, E) All these drugs are not suitable for hypertensive emergencies since their onset of action is
too slow
18.
A 56-year-old woman recently diagnosed with hypertension and atrial fibrillation
started a treatment with atenolol, two tablets daily. Which of the following sets of
physiologic changes was most likely after the administration of the drug?
Correct Answer
A. A
Explanation
Learning objective: describe the hemodynamic effects of atenolol
Answer: A
Atenolol is a selective beta-1 blocker. Therefore cardiac output is decreased because of the
decrease in cardiac contractility and rate, venous tone is unchanged since beta-1 receptors are not located on the vessels and postural hypotension is negligible since the drug does not cause
hypovolemia and the baroreceptor reflex is unaffected.
B, C, D, E) (see explanation above)
19.
A 56-year-old man complained to his physician of palpitations, sweating and flushing
of two day duration. The man, who had been suffering from hypertension for 3 months,
had started a therapy with hydrochlorothiazide and captopril but one month later his
blood pressure was still 170/100 mm Hg. One week ago the physician decided to add a
third antihypertensive agent to the treatment. Which of the following drugs was most
likely added to the patient’s therapy?
Correct Answer
A. Hydralazine
Explanation
Learning objective: describe the main adverse effects of hydralazine
Answer: A
Hydralazine is an arteriolar vasodilator that causes reflex tachycardia which explains the
subjective feeling of palpitations. Skin vasodilation causes sweating and flushing.
B, C, D) All these drugs tend to cause bradycardia, so palpitations are quite unlikely.
E) Nitroprusside can cause tachycardia an flushing. However it is used only in hypertensive
emergencies, since its half-life is very short.
20.
A 61-year-old man, suffering from stage 2 hypertension for many years, had minoxidil
added recently to his antihypertensive therapy. Which of the following actions best
explains the antihypertensive effect of this drug?
Correct Answer
E. Decreased total peripHeral resistance
Explanation
Learning objective: describe the actions leading to the therapeutic effect of minoxidil.
Answer: E.
Minoxidil acts by opening potassium channels in smooth muscle cell membrane, which leads to
membrane stabilization, so making contraction less likely. Vasodilation is limited to the
arterioles (effect on capacitance vessels is negligible) and causes the reduction of total
peripheral resistance.
A, B), Minoxidil causes a reflex activation of the sympathetic nervous system, which results in
effects opposite to those listed
C, D) Minoxidil has no effect on extracellular fluid volume and on the synthesis of angiotensin II.
21.
A 34-year-old woman complained of itching and burning around her vagina and a foul-smelling vaginal discharge. A wet mount examination of the discharge showed pear-shaped trophozoites that exhibited jerky motility. Which of the following drugs would be appropriate for this patient?
Correct Answer
D. Metronidazole
Explanation
The symptoms and the lab exam of the patient clearly indicate that she was suffering from trichomoniasis. Metronidazole is the drug of choice for this disease. A, B, C, E, F) These drugs are not effective against trichomoniasis.
22.
A 35-year-old woman, back from a tourist trip in the Amazona forest, developed a red papule in her right arm, which enlarged slowly and began to ulcerate but caused no pain. A few days later multiple lesions developed. A smear taken from the skin lesions demonstrated the presence of amastigotes. Which of the following drugs would be appropriate for this patient?
Correct Answer
B. Sodium stibogluconate
Explanation
Answer: B The history, signs and lab exams of the patient clearly indicate that she was most likely suffering from cutaneous leismaniasis. Drugs of choice for leismaniasis include pentamidine, amphotericin B, antimony compounds (like sodium stibogluconate) and certain azoles (itraconazole). A, C, D, E, F) These drugs are not effective against leismaniasis.
23.
What is the mechanism of action of Clindamycin?
Correct Answer
B. Reversibly binds to 50S ribosomal subunits, preventing peptide bond formation, thus inhibiting bacterial protein synthesis.
Explanation
The correct mechanism of action of Clindamycin is: "Reversibly binds to 50S ribosomal subunits preventing peptide bond formation thus inhibiting bacterial protein synthesis." Clindamycin is a protein synthesis inhibitor that binds to the 50S ribosomal subunit of bacteria, interfering with peptide bond formation during protein synthesis. This disrupts bacterial protein production, leading to the inhibition of bacterial growth.
24.
Which of the following antiprotozoal medications is used to treat both malaria and extraintestinal amebiasis?
Correct Answer
A. Tinidazole
Explanation
Tinidazole is an antiprotozoal medication used to treat both malaria and extraintestinal amebiasis. It works by interfering with the DNA structure of the protozoa, making it difficult for them to replicate and survive in the body. In the case of malaria, tinidazole targets the malaria parasite, Plasmodium, disrupting its DNA replication and killing the parasites responsible for the infection. For extraintestinal amebiasis, which is caused by the parasite Entamoeba histolytica, tinidazole is effective in treating the infection by damaging the DNA of the amebic parasite, preventing its growth and causing it to die off. Tinidazole is a valuable medication for combating these protozoal infections and is particularly useful in cases where other treatments may not be as effective.
25.
Which medication is used to prevent and treat Pneumocystis jirovecii pneumonia (PCP) in immunocompromised individuals?
Correct Answer
C. Trimethoprim-sulfamethoxazole
Explanation
Trimethoprim-sulfamethoxazole, often abbreviated as TMP-SMX, is commonly used to prevent and treat Pneumocystis jirovecii pneumonia (PCP) in immunocompromised individuals. It is an effective antibiotic combination for the prophylaxis and treatment of PCP, which is an opportunistic infection often seen in individuals with weakened immune systems, such as those with HIV/AIDS.
26.
A 43-year-old man is about to leave for a vacation trip to central America. He is advised by his physician to take mefloquine as a prophylactic measure, since he knew that chloroquine resistance was widespread and increasing. Which of the following phrase best explains the likely mechanism of plasmodial resistance to chloroquine?
Correct Answer
C. Increased drug transport outside plasmodia cells
Explanation
Answer: C Chloroquine acts by getting accumulated in the food vacuole where it inhibits heme polymerase. Resistant strains are able to efflux the drug by an active pump mechanism and release the drug at least 40 times faster than sensitive strains, thereby rendering the drug ineffective. Chloroquine resistance is maintained throughout the whole life cycle and is transferred to the progeny. Crossresistance has been demonstrated with other 4-amino quinolines, but not to quinine, mefloquine, or antifolates.
27.
A 45-year-old reporter who was about to leave for Honduras, started a prophylactics antimalarial treatment with chloroquine. Which of the following molecular actions most likely mediate the therapeutic effect of this drug?
Correct Answer
E. Prevention of polymerization of free heme into hemozoin
Explanation
Answer: E Malarial parasites grow in host erythrocytes by ingesting hemoglobin, a process that generates free radicals and heme as highly reactive by products. Heme polymerizes into an unreactive malarial pigment called hemozoin. Chloroquine inhibits plasmodial heme polymerase, the enzyme that polymerizes heme into hemozoin and the build up of free heme causes the death of parasites. A, B, C, D) (see explanation above)
28.
A. The 41-year-old woman, coming back from a trip to Kenya, was admitted to the hospital because of malaise, myalgia, abdominal pain, and fever (104 F). The recent history of the patient was significant for two paroxysmal attacks of chills, fever, and vomiting. The first attack lasted a day and was followed by a second 36 hours later. Physical examination revealed an acutely hill patient complaining of severe abdominal pain. Palpation showed a tender, soft, and enlarged spleen. Examination of a stained blood specimen revealed ringlike and crescent-like forms within the RBCs. Which of the following pairs of drugs would be appropriate for this patient?
Correct Answer
A. Quinidine and doxycycline
Explanation
Answer: A The history and the signs of the patient together with the lab results indicate that he was most likely affected by falciparum malaria. Since infections with P falciparum in non immune patients can progress rapidly to a fatal outcome therapy should be initiated promptly. Chinchona alkaloids (quinine or quinidine) are the treatment of choice for severe falciparum malaria. They are usually given with a second drug (most often doxycycline) to shorten the duration of treatment and to limit toxicity. B, C, D, E) (see explanation above)
29.
What is the recommended treatment for African sleeping sickness, a protozoan infection caused by Trypanosoma brucei?
Correct Answer
D. Pentamidine
Explanation
The recommended treatment for African sleeping sickness, a protozoan infection caused by Trypanosoma brucei, is c. Pentamidine. Pentamidine is an antiprotozoal medication used to treat both the early and late stages of African sleeping sickness, depending on the specific subspecies of the parasite involved. It is administered intravenously and works by disrupting the DNA and other cellular functions of the trypanosome parasites, effectively killing them and treating the infection. This medication is a crucial component of efforts to control and manage African sleeping sickness in affected regions.
30.
A 35-year-old woman was planning a trip to malaria endemic regions of central America. She was advised by her physician to take a tablet of pyrimethamine-sulfadoxine (fansidar) in case of fever and then to obtain as soon as possible medical attention. The antimalarial efficacy of pyrimethamine is most likely mediated by the inhibition of which of the following protozoal enzymes?
Correct Answer
E. Dihydrofolate reductase
Explanation
Answer: E Pyrimethamine selectively inhibit plasmodial dihydrofolate reductase, a key enzyme for the synthesis of DNA. This leads to failure in nuclear division at the time of schizonts formation in the blood and liver. Resistance to the drug develops in regions of prolonged and extensive drug use and is related to several different mutation of th enzyme. A, B, C, D) (see explanation above)
31.
A 34-year-old woman complained of itching and burning around her vagina and a foulsmelling vaginal discharge. A wet mount examination of the discharge showed pear-shaped trophozoites that exhibited jerky motility. Which of the following drugs would be appropriate for this patient?
Correct Answer
D. Metronidazole
Explanation
The symptoms and the lab exam of the patient clearly indicate that she was suffering from trichomoniasis. Metronidazole is the drug of choice for this disease. A, B, C, E, F) These drugs are not effective against trichomoniasis.
32.
A 35-year-old woman, back from a tourist trip in the Amazona forest, developed a red papule in her right arm, which enlarged slowly and began to ulcerate but caused no pain. A few days later multiple lesions developed. A smear taken from the skin lesions demonstrated the presence of amastigotes. Which of the following drugs would be appropriate for this patient?
Correct Answer
B. Sodium stibogluconate
Explanation
Answer: B The history, signs and lab exams of the patient clearly indicate that she was most likely suffering from cutaneous leismaniasis. Drugs of choice for leismaniasis include pentamidine, amphotericin B, antimony compounds (like sodium stibogluconate) and certain azoles (itraconazole). A, C, D, E, F) These drugs are not effective against leismaniasis.
33.
A 23-year-old man, coming back from a trip to Peru complained of abdominal discomfort and occasional foul-smelling diarrhea alternating with constipation of a 2-week duration. Stools culture was negative for bacterial pathogens. Which of the following drugs would be an appropriate empiric treatment for the patient at this time?
Correct Answer
C. Metronidazole
Explanation
Answer: C The history and symptoms of the patient and the negative bacterial culture indicate that he was most likely suffering from an intestinal protozoal infection. The two most common protozoal infections of the gastrointestinal tract are amebiasis and giardiasis. Both can be effectively treated with metronidazole and therefore the drug represents the best empiric treatment. A, B, D, E, F) These drug are not effective against intestinal amebiasis or giardiasis
34.
A 42-year-old man recently admitted to a mental hospital because of a schizoaffective disorder, complained of diarrhea and stomach cramps. Trophozoites and cysts were observed in his stools specimen. A duodenum string test was also positive for heart-shaped trophozoites with 4 pairs of flagella. Which of the following drugs would be appropriate for this patient?
Correct Answer
B. Metronidazole
Explanation
Answer: B The symptoms and the lab exam of the patient (heart-shaped trophozoites with 4 pairs of flagella) clearly indicate that he is suffering from giardiasis. Metronidazole is the drug of choice for this disease. A) G. lambia is also sensitive to paromomycin, but the drug is a second line agent since it is much less effective than metronidazole. C, D, E, F) These drugs are not effective against giardiasis.
35.
A 24-year-old woman, who was 22-week pregnant, presented with a 5-day history of loose stools containing bloody mucus. Her past medical history was significant for an optic neuritis one month ago, apparently due to a viral infection. Upon physical examination, her abdomen was soft but nontender. The exam of fresh stools showedE. histolytica trophozoites. A CT scan was negative for gut wall or liver amebiasis.Which of the following drugs would be appropriate for this patient?
Correct Answer
D. Paromomycin
Explanation
Answer: D The symptoms of the patient and the lab exam indicate that she was suffering from amebic dysentery. Since the patient apparently has no extraintestinal amebiasis (see the negative CT scan) a luminal amebicide is appropriate. Paromomycin is a second line luminal amebicide. In this patient however metronidazole is contraindicated because of pregnancy and the previous optic neuritis. A) (see explanation above) B) Chloroquine is only effective against liver amebiasis. C, E, F) These drugs are not effective against E. histolytica.
36.
A 31-year-old homosexual man presented to the hospital with a 10-day history of abdominal pain and multiple, brown, watery stools. Physical examination revealed a tall man with abdominal distress. Vital signs were: blood pressure 125/75 mm Hg, pulse 78 bpm, temperature 103.5° F. His abdomen was slightly distended with a tender mass palpable in the lower right quadrant, which proved to be an abdominal abscess on ultrasound examination. A serologic test was positive for E . histolytica .Which of the following pairs of drugs would be appropriate for this patient?
Correct Answer
A. Metronidazole and iodoquinol
Explanation
Answer: A The symptoms of the patient and the lab exam indicate that he was suffering from an amebic abscess presumably located on the gut wall (ameboma). For extraintestinal amebiasis metronidazole is the drug of choice. A luminal amebicide (like iodoquinol or paromomycin) must be given concomitantly in order to eradicate the infection. B, C, D, E, F) In these drug combinations at least one drug is not active against. E . histolytica
37.
A 34-year-old black man permanent US is planning to visit his seriously ill father who lives in Uganda. He will be accompanied by his wife and son. Knowing that chloroquine-resistant strains of malaria are present in Uganda, which of the following drugs used alone should be administered to the man, his wife, and son before entering Uganda?
Correct Answer
D. Mefloquine
Explanation
Answer: D Resistance to chloroquine is now very common in many Africa areas. Mefloquine is a drug with strong schizonticidal activity and is effective against many chloroquine resistant strains of P. Falciparum and other malaria species. Other regimens for malaria chemoprophylaxis in regions with multidrug resistant strains of P. Falciparum include doxycycline and pyrimethaminesulfadoxine combination (Fansidar). A) Primaquine is the only antimalarial drug active against the hypnozoite stages of P. Vivax and P ovale. Because of this some authors advocate the use of the drug after the travel to an endemic area. B) Metronidazole is not active against plasmodia. C, E) Chemoprophylaxis with these drugs is not recommended because of frequent resistance but they are used in combination regimens. F) Even if most chloroquine-resistant strains of P. Falciparum are sensitive to quinine, the drug is not used for prophylaxis because of its toxicity.
38.
A 33-year-old man was planning a vacation to sub-Saharan Africa where chloroquine-resistant strains of P. falciparum are present. Which of the following drugs combinations would be appropriate to prevent infection in this man?
Correct Answer
C. Pyrimethamine-sulfadoxine
Explanation
Answer: C Pyrimethamine-sulfadoxine (Fansidar) is an effective prophylactic regimen for chloroquine-resistant P. falciparum. However the rates of resistance to this drug combination are increasing and this regimen is less optimal than mefloquine or quinine, especially for non immune individuals A, B, D, E) In these drug combinations at least one drug is not active against P. falciparum
39.
A 31-year-old man, coming back from a trip to Malaysia, was admitted to the hospital with a two day history of fever, chills and bouts of diarrhea. A Giemsa blood smear demonstrated P. Vivax trophozoites. The patient was placed on chloroquine for 5 days, then he was instructed to take another drug for 14 days.Which of the following drugs was most likely prescribed?
Correct Answer
A. Primaquine
Explanation
Answer: A Primaquine is the only agent able to prevent relapse of infection due to the late exoerythrocytic stage of P vivax and P. Ovale. It is therefore commonly given to achieve a radical cure of vivax or ovale malaria. B, C, D, E, F) (see explanation above)
40.
A 45-year-old black man referred to his physician that few days ago he noticed a persistent yellow color in his eyes . One week before, coming back from a trip to central America, the man had started a treatment which included primaquine. A blood test disclosed the following:RBC count: 3.8 x 106/ mm3 (normal: 4-5.5)Hb: 9 g/dL (normal: > 12)Reticulocytes: 3.7% of red cells (normal 0.5-1.5%)WBC count 12000/mm3 (normal: 3200-9800)The physician told the patient that he probably had a genetically induced enzyme defect. Which of the following enzymes was most likely abnormal?
Correct Answer
E. Glucose-6-pHospHate-dehydrogenase
Explanation
Answer: E The history and the lab exams of the patient indicate that he was suffering from hemolytic anemia. The disorder was most likely triggered by primaquine in a person with a genetically induced glucose-6-phosphate-dehydrogenase deficiency. G6PD is a X-linked disorder. Over 100 mutant forms of the enzyme have been identified, but the drug sensitive variety is the most common. The enzyme defect occurs in about 10% of American black males. Hemolysis affects the older RBCs after exposure to drugs that produce peroxide and cause oxidation of RBC membranes. These drugs include primaquine and other antimalarias (chloroquine, quinine) salicylates and sulfonamides. The degree of hemolytic anemia varies greatly. Jaundice, reticulocytosis and leukocytosis are common, like in the present case. A, B, C, D) (see explanation above)
41.
A 55-year-old man, who was about to leave for a vacation trip to central Africa, started a treatment with mefloquine. Which of the following plasmodia cells can be effectively killed by the drug?
Correct Answer
E. P. Malarie blood schizonts
Explanation
Answer: E Mefloquine is a blood schizonticide and is moderately effective against gametocytes, except those of P. Falciparum. It has no effect on primary tissue schizonts or hypnozoites. A, B, C, F) (see explanation above)
42.
What class of drugs is commonly used to treat protozoan infections such as malaria and toxoplasmosis?
Correct Answer
C. Antiprotozoal agents
Explanation
Antiprotozoal agents are commonly used to treat protozoan infections such as malaria and toxoplasmosis. These drugs are specifically designed to target and combat protozoan parasites responsible for various infections in humans. Antiprotozoal agents work through different mechanisms to inhibit the growth, replication, or survival of protozoa within the host's body. The choice of antiprotozoal agent may vary depending on the specific parasite and infection being treated, as different drugs may be more effective against particular protozoan species.
43.
What is the primary mode of action of antiprotozoal drugs against protozoan parasites?
Correct Answer
C. Inhibition of protozoan DNA synthesis or function
Explanation
Antiprotozoal drugs primarily work by inhibiting the DNA synthesis or essential functions of protozoan parasites, which are single-celled microorganisms responsible for various infectious diseases. These drugs interfere with the vital processes that allow protozoa to replicate and thrive within the host's body. By targeting their DNA or critical cellular functions, antiprotozoal drugs disrupt the parasite's ability to survive and reproduce, ultimately leading to its elimination from the host's system. This mode of action is crucial in treating diseases caused by protozoa, such as malaria and trypanosomiasis, as it helps control and eradicate the infections. The use of these drugs is a vital component of global efforts to combat parasitic diseases and protect public health.
44.
A 45-year-old reporter who was about to leave for Honduras, started a prophylactics antimalarial treatment with chloroquine. Which of the following molecular actions most likely mediate the therapeutic effect of this drug?
Correct Answer
E. Prevention of polymerization of free heme into hemozoin
Explanation
Answer: E Malarial parasites grow in host erythrocytes by ingesting hemoglobin, a process that generates free radicals and heme as highly reactive by products. Heme polymerizes into an unreactive malarial pigment called hemozoin. Chloroquine inhibits plasmodial heme polymerase, the enzyme that polymerizes heme into hemozoin and the build up of free heme causes the death of parasites. A, B, C, D) (see explanation above)
45.
Which medication is commonly used to treat amoebic dysentery and liver abscess caused by Entamoeba histolytica?
Correct Answer
B. Metronidazole
Explanation
The medication commonly used to treat amoebic dysentery and liver abscess caused by Entamoeba histolytica is b. Metronidazole. Metronidazole is the preferred treatment for these parasitic infections due to its effectiveness in eradicating the parasite. It works by disrupting the DNA and other essential molecules within the parasite's cells, ultimately leading to its death. This drug is well-absorbed in the gastrointestinal tract and has good tissue penetration, making it effective against the amoeba in various parts of the body. Metronidazole is typically administered orally or intravenously under medical supervision, and a full course of treatment is necessary to ensure complete eradication of the parasite and prevent the recurrence of the infection.