Practice Questions! (renal pharm)

A 12-year-old child has bacterial pharyngitis and is to receive an oral antibiotic. She complains of a sore throat and pain on swallowing. The tympanic membranes are slightly reddened bilaterally, but she does not complain of earache. Blood pressure is 105/70 mm Hg, heart rate 100/mm, temperature 37.8 °C (100.1 °F). Ampicillin is a weak organic acid with a pKa of 2.5. What percentage of a given dose will be in the lipid-soluble form in the duodenum at a pH of 4.5? A About 1% B About 10% C About 50% D About 90% E About 99%

A

Sugammadex is a new drug that reverses the action of rocuronium and certain other skeletal muscle-relaxing agents (nondepolarizing neuromuscular blocking agents). It appears to interact directly with the rocuronium molecule and not at all with the rocuronium receptor. Which of the following terms best describes sugammadex? A Chemical antagonist B Noncompetitive antagonist C Partial agonist D Pharmacologic antagonist E Physiologic antagonist

A

Which of the following statements about new drug development is most correct? A Drugs that test positive for teratogenicity, mutagenicity, or carcinogenicity can be tested in humans B Food supplements and herbal (botanical) remedies are subject to the same FDA regulation as ordinary drugs C All new drugs must be studied in at least 1 primate species before NDA submission D Orphan drugs are drugs that are no longer produced by the original manufacturer E Phase 4 (surveillance) is the most rigidly regulated phase of clinical drug trials

A

A 3-year-old is brought to the emergency department having just ingested a large overdose of tolbutamide, an oral antidiabetic drug. Tolbutamide is a weak acid with a pKa of 5.3. It is capable of entering most tissues, including the brain. On physical examination, the heart rate is 100/min, blood pressure 90/50 mm Hg, and respiratory rate 20/min. Which of the following statements about this case of tolbutamide overdose is most correct? A Urinary excretion would be accelerated by administration of NH4Cl, an acidifying agent B Urinary excretion would be accelerated by giving NaHCO3, an alkalinizing agent C Less of the drug would be ionized at blood pH than at stomach pH D Absorption of the drug would be slower from the stomach than from the small intestine E Hemodialysis is the only effective therapy

B

Gentamicin, an aminoglycoside antibiotic, is sometimes given in intermittent intravenous bolus doses of 100 mg 3 times a day to achieve target peak plasma concentrations of about 5 mg/L. Gentamicin's clearance (normally 5.4 L/h/70 kg) is almost entirely by glomerular filtration. Your patient, however, is found to have a creatinine clearance one third of normal. What should your modified dosage regimen for this patient be? A 20 mg 3 times a day B 33 mg 3 times a day C 72 mg 3 times a day D 100 mg 2 times a day E 150 mg 2 times a day

B

A 3-year-old child is admitted to the emergency department after taking a drug from her parents' medicine cabinet. The signs suggest that the drug is an indirect-acting cholinomimetic with little or no CNS effect and a duration of action of about 2-4 h. Which of the following is the most likely cause of these effects? A Acetylcholine B Bethanechol C Neostigmine D Physostigmine E Pilocarpine

C

Nicotinice receptors are not present in? A. Autonomic ganglia B. NMJ of skeletal muscle C. Bronchial smooth muscle D. Adrenal medulla

C

Which of the following is an accepted therapeutic indication for the use of antimuscarinic drugs? A Atrial fibrillation B Botulinum poisoning C Chronic obstructive pulmonary disease (COPD) D Glaucoma E Postoperative urinary retention

C

A study was carried out in isolated intestinal smooth muscle preparations to determine the action of a new drug "novamine," which in separate studies bound to the same receptors as acetylcholine. In the absence of other drugs, acetylcholine caused contraction of the muscle. Novamine alone caused relaxation of the preparation. In the presence of a low concentration of novamine, the EC50 of acetylcholine was unchanged, but the Emax was reduced. In the presence of a high concentration of novamine, extremely high concentrations of acetylcholine had no effect. Which of the following expressions best describes novamine? A A chemical antagonist B An irreversible antagonist C A partial agonist D A physiologic antagonist E A spare receptor agonist

Choices involving chemical or physiologic antagonism are incorrect because novamine is said to act at the same receptors as acetylcholine. When given alone, the novamine effect is opposite to that of acetylcholine, so choice C is incorrect. "Spare receptor agonist" is a nonsense distracter. The answer is B.

The pharmacokinetic process or property that distinguishes the elimination of ethanol and high doses of phenytoin and aspirin from the elimination of most other drugs is called A Distribution B Excretion C First-pass effect D First-order elimination E Zero-order elimination

E

Which of the following cytochrome isoforms is responsible for metabolizing the largest number of drugs? A CYP1A2 B CYP2C9 C CYP2C19 D CYP2D6 E CYP3A4

E

Which of the following would probably not be included in an optimal phase 3 clinical trial of a new analgesic drug for mild pain? A A negative control (placebo) B A positive control (current standard analgesic therapy) C Double-blind protocol (in which neither the patient nor immediate observers of the patient know which agent is active) D A group of 1000-5000 subjects with a clinical condition requiring analgesia E Prior submission of an NDA (new drug application) to the FDA

E

You are the only physician in a clinic that is cut off from the outside world by violent storms, flooding, and landslides. A 15-year-old girl is brought to the clinic with severe asthmatic wheezing. Because of the lack of other drugs, you decide to use intravenous theophylline for treatment. The pharmacokinetics of theophylline include the following average parameters: Vd 35 L; CL 48 mL/min; half-life 8 h. If an intravenous infusion of theophylline is started at a rate of 0.48 mg/min, how long would it take to reach 93.75% of the final steady-state concentration? A Approximately 48 min B Approximately 7.4 h C Approximately 8 h D Approximately 24 h E Approximately 32 h

E

Mr Green, a 54-year-old banker, had a cardiac transplant 6 months ago. His current blood pressure is 120/70 mm Hg and heart rate is 100 bpm. Which of the following drugs would have the least effect on Mr Green's heart rate? A Albuterol B Epinephrine C Isoproterenol D Norepinephrine E Phenylephrine

Heart transplantation involves cutting of the autonomic nerves to the heart. As a result, autonomic nerve endings degenerate, and cardiac transmitter stores are absent for 2 years or longer after surgery. Therefore, indirect-acting sympathomimetics are ineffective in changing heart rate. All the drugs listed are direct-acting, and all but phenylephrine have significant effects on β receptors. Phenylephrine usually causes reflex bradycardia, which requires intact vagal innervation. The answer is E. (Note that denervation may result in upregulation of both β1 and β2 receptors so that direct-acting β agonists may have a greater than normal effect.)

Which of the following is an expected effect of a therapeutic dose of an antimuscarinic drug? A Decreased cAMP (cyclic adenosine monophosphate) in cardiac muscle B Decreased DAG (diacylglycerol) in salivary gland tissue C Increased IP3 (inositol trisphosphate) in intestinal smooth muscle D Increased potassium efflux from smooth muscle E Increased sodium influx into the skeletal muscle end plate

Muscarinic M1 and M3 receptors mediate increases in IP3 and DAG in target tissues (intestine, salivary glands). M2 receptors (heart) mediate a decrease in cAMP and an increase in potassium permeability. Antimuscarinic agents block these effects. The answer is B.

Graded and quantal dose-response curves are being used for evaluation of a new antiasthmatic drug in the animal laboratory and in clinical trials. Which of the following statements best describes graded dose-response curves? A More precisely quantitated than quantal dose-response curves B Obtainable from isolated tissue preparations but not from the study of intact subjects C Used to determine the maximal efficacy of the drug D Used to determine the therapeutic index of the drug E Used to determine the variation in sensitivity of subjects to the drug

Precise quantitation is possible with both types of dose-response curves. Quantal dose-response curves show the frequency of occurrence of a specified response, which may be therapeutically effective (ED) or toxic (TD). Thus, quantal studies are used to determine the therapeutic index and the variation in sensitivity to the drug. Graded (not quantal) dose-response curves are used to determine maximal efficacy (maximal response). The answer is C.