Home Books Katzung & Trevor's Pharmacology: Examination & Board Review, 12e

Chapter 16: Histamine, Serotonin, Drugs Used in Obesity, & the Ergot Alkaloids

Your 37-year-old patient has been diagnosed with a rare metastatic carcinoid tumor. This neoplasm is releasing serotonin, bradykinin, and several unknown peptides. The effects of serotonin in this patient are most likely to include

(A) Constipation

(B) Episodes of bronchospasm

(C) Hypersecretion of gastric acid

(D) Hypotension

(E) Urinary retention

Serotonin causes bronchospasm, but the other effects listed are not observed. Carcinoid is associated with diarrhea and hypertension. The answer is B.

A 23-year-old woman is admitted to the emergency department with difficulty breathing. Examination reveals significant laryngeal edema. Past medical history indicates that she suffers from recurrent episodes of angioneurotic edema with release of histamine and other mediators. Which of the following drugs is the most effective physiologic antagonist of histamine in smooth muscle?

(A) Epinephrine

(B) Loratadine

(C) Ondansetron

(D) Ranitidine

(E) Sumatriptan

The smooth muscle effects of histamine are mediated mainly by H₁ receptors. Loratadine is a pharmacologic antagonist of histamine at these receptors. Ondansetron is a 5-HT₃ antagonist used to prevent postsurgical and chemotherapy-induced vomiting. Sumatriptan is a 5-HT_1D/1B agonist. Ranitidine is a pharmacologic histamine antagonist that blocks the H₂ receptor in the stomach and the heart, not H₁ receptors in smooth muscle. Epinephrine has a physiologic antagonist action that reverses histamine’s effects on smooth muscle. The answer is A.

A 20-year-old woman is taking over-the-counter diphenhydramine for severe hay fever. Which of the following adverse effects is she most likely to report?

(A) Muscarinic increase in bladder tone

(B) Nausea

(C) Nervousness, anxiety

(D) Sedation

(E) Vertigo

H₁ blockers do not activate muscarinic receptors, mediate vasoconstriction, or cause vertigo. Some relieve vertigo or motion sickness. They do not cause nervousness or anxiety. Diphenhydramine is a potent sedative with H₁- and M₃-blocking actions. The answer is D.

A laboratory study of new H₂ blockers is planned. Which of the following will result from blockade of H₂ receptors?

(A) Increased cAMP (cyclic adenosine monophosphate) in cardiac muscle

(B) Decreased channel opening in enteric nerves

(C) Decreased cAMP in gastric mucosa

(D) Increased IP₃ (inositol trisphosphate) in platelets

(E) Increased IP₃ in smooth muscle

H₂ receptors are G_s-protein-coupled receptors, like β adrenoceptors. Blockade of this system will cause a decrease in cAMP in several tissues. The answer is C.

An obese 40-year-old man (BMI 31) is being seen in the cardio-pulmonary clinic for pulmonary hypertension and a cardiac murmur. He took fenfluramine for several years in an attempt to reduce his weight. The mechanism by which fenfluramine affected appetite is:

(A) 5-HT₂ agonist action

(B) Amphetamine-mimetic action

(C) Anti-opioid/antidepressant action

(D) Glucagon-like peptide (GLP) agonist action

(E) Intestinal lipase inhibition

Refer to Table 16–3. Fenfluramine, a 5-HT_2c agonist, is now banned because it caused pulmonary hypertension and cardiac valve malfunction. Phentermine has an amphetamine-like action. Naltrexone is a long-acting opioid antagonist; bupropion is an antidepressant. Liraglutide is a GLP-1 agonist. Orlistat is an inhibitor of intestinal lipase. The answer is A.

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Table 16–3. Anti-obesity drugs and their effects.

Drug or Drug Combination

Drug Group

Possible Mechanism of Action

Dosage

Toxicity

Orlistat

GI lipase inhibitor

Reduces lipid absorption

60–120 mg TID PO

Decreased absorption of fat-soluble vitamins, flatulence, fecal incontinence

Liraglutide

GLP-1 agonist

Decreases appetite

3 mg/d SC

Nausea, vomiting, pancreatitis

Lorcaserin

5-HT_2c agonist

Decreases appetite

10 mg PO BID

Headache, nausea, dry mouth, dizziness, constipation

Naltrexone/bupropion

Opioid antagonist + antidepressant

Unknown

32 mg/360 mg PO TID

Headache, nausea, dizziness, constipation

Phentermine

Sympathomimetic

Norepinephrine release in CNS

30–37.5 mg/d PO

Increased BP, HR; arrhythmias, insomnia, anxiety

Phentermine/topiramate

Sympathomimetic + antiseizure agent

Norepinephrine release plus unknown mechanism

3.75–15 mg/23–92 mg PO

Insomnia, dizziness, nausea, paresthesia, dysgeusia

BID, twice daily; BP, blood pressure; CNS, central nervous system; GI, gastrointestinal; HR, heart rate; PO, by mouth; SC, subcutaneously; TID, three times daily.

Reproduced, with permission, from Katzung BG, editor: Basic & Clinical Pharmacology, 14th ed. McGraw-Hill, 2018.

A 40-year-old patient with breast cancer is about to undergo cancer chemotherapy with a highly emetogenic (nausea- and vomiting-causing) drug combination. The antiemetic drug most likely to be included in her regimen is

(A) Bromocriptine

(B) Cetirizine

(C) Cimetidine

(D) Ketanserin

(E) Ondansetron

Ondansetron and other 5-HT₃ antagonists have significant antiemetic effects. Diphenhydramine and prednisone are also used for this purpose. The answer is E.

The hospital pharmacy committee is preparing a formulary for staff use. Which of the following is a correct application of the drug mentioned?

(A) Alosetron: for obstetric bleeding

(B) Cetirizine: for hay fever

(C) Ergonovine: for Alzheimer’s disease

(D) Ondansetron: for acute migraine headache

(E) Ranitidine: for Parkinson’s disease

Alosetron is indicated in irritable bowel syndrome. Ergonovine is used in uterine bleeding. Ondansetron is useful for chemotherapy-induced emesis. Cetirizine, a second-generation H₁ blocker, is used in the treatment of hay fever. The answer is B.

A 26-year-old woman presents with amenorrhea and galactorrhea. Her prolactin level is grossly elevated (200 ng/mL vs normal 20 ng/mL). Which of the following is most useful in the treatment of hyperprolactinemia?

(A) Bromocriptine

(B) Cimetidine

(C) Ergotamine

(D) Ketanserin

(E) LSD

(F) Ondansetron

(G) Sumatriptan

Bromocriptine is an effective dopamine agonist in the CNS with the advantage of oral activity. The drug inhibits prolactin secretion by activating pituitary dopamine receptors. The answer is A.

A 28-year-old office worker suffers from intense migraine headaches. Which of the following is a serotonin 5-HT_1D/1B agonist useful for aborting an acute migraine headache?

(A) Bromocriptine

(B) Cimetidine

(C) Ephedrine

(D) Ketanserin

(E) Loratadine

(F) Ondansetron

(G) Sumatriptan

Sumatriptan, an agonist at 5-HT_1D/1B receptors, is indicated for prevention or treatment of migraine and cluster headaches. Ergotamine (not on the list) is also effective for acute migraine but is produced by the fungus Claviceps purpurea. The answer is G.

A 33-year-old woman attempted to induce an abortion using ergotamine. She is admitted to the emergency department with severe pain in both legs. On examination, her legs are cold and pale with absent arterial pulses. Which of the following is the most useful antidote for reversing severe ergot-induced vasospasm?

(A) Bromocriptine

(B) Cimetidine

(C) Ergotamine

(D) Ketanserin

(E) LSD

(F) Nitroprusside

(G) Sumatriptan

(H) Ondansetron

A very powerful vasodilator is necessary to reverse ergot-induced vasospasm; nitroprusside is such a drug (see Chapter 11). The answer is F.

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Chapter 16: Histamine, Serotonin, Drugs Used in Obesity, & the Ergot Alkaloids

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