Pharmacology Antihypertensive Drugs Quiz

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.

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.

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

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)

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.

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.

Fenoldopam is the correct answer because it activates D1 receptors. The other drugs listed do not have this mechanism of action.

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)

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)

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

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.

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.

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.

ACE inhibitors are a class of drugs commonly used to treat hypertension and other cardiovascular conditions. They work by inhibiting the angiotensin-converting enzyme, which is involved in the production of angiotensin II, a hormone that constricts blood vessels and increases blood pressure. While ACE inhibitors are generally well-tolerated, they can cause some side effects, including dry cough, angioedema (swelling of the face, lips, or tongue), and hyperkalemia (elevated potassium levels). Tachycardia, which is a rapid heart rate, is not a typical side effect of ACE inhibitors. In fact, ACE inhibitors can sometimes cause bradycardia, which is a slow heart rate.

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

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.

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)

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.

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.

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)

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.

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.

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)

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.

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.

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.

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.

Calcium channel blockers are a class of antihypertensive drugs that work by blocking the entry of calcium into muscle cells in the heart and blood vessels. This leads to vasodilation and a decrease in blood pressure. While calcium channel blockers can cause some side effects, such as headache, dizziness, and flushing, they are not typically associated with orthostatic hypotension, which is a sudden drop in blood pressure upon standing. Orthostatic hypotension is more commonly seen with alpha-blockers, beta-blockers, and diuretics, which can affect the body's ability to regulate blood pressure in response to changes in posture.

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.

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.

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)

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.

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

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.

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)

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.