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USMLE Step 1 Pharmacology

Subjects : health-sciences, usmle-step-1

Instructions:

Answer 50 questions in 15 minutes.
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Match each statement with the correct term.
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This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. How do Sulfonamides act on bacteria?
Overdose produces hepatic necrosis; acetaminophen metablolite depletes glutathione and forms toxic tissue adducts in liver.
It would increase to ~ 100 beats/min. Both sympathetic and vagal stimulation would be knocked out - but the SA node has an intrinsic pace of 100 beats/min - Which is normally checked by vagal stimulation.
As PABA antimetabolites that inhibit Dihydropteroate Synthase - Bacteriostatic
- Clindamycin

2. What side effect of using atropine to induce pupillary dilation would you expect?
loop diuretics - thiazides
- polymyxins
- Normalize K+ - Lidocaine - & Anti - dig Mab
Atropine would also block the receptors in the ciliary muscle - causing an impairment in accommodation (cycloplegia).

3. Are not penicillinase resistant
Paranteral (IV - SC)
Chronic gout.
Carbenicillin - Piperacillin - and Ticarcillin
Reversibly inhibits cyclooxygenase - mostly in CNS. Inactivated peripherally.

4. What are common serious side effects of Aminoglycosides and What are these associated with?
Nephrotoxicity (esp. with Cephalosporins) - Ototoxicity (esp. with Loop Diuretics)
The COX-2 inhibitors should not have the corrosive effects of other NSAIDs on the gastrointestinal lining.
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.
Phenothiazine (neuroleptic - antiemetic).

5. What type of neurological blockade would hexamethonium create?
cholestyramine - colestipol
Hexamethonium is a nicotinic antagonist - and thus is a ganglionic blocker.
impotence - asthma - CV effects (bradycardia - CHF - AV block) - CNS effects (sedation - sleep alterations)
- acetylation - glucuron. - & sulfation - Conjugation - Polar product

6. Which individuals are predisposed to Sulfonamide - induced hemolysis?
pulmonary edema - dehydration
G6PD deficient individuals
Inhibits platelet aggregation by irreversibly inhibiting the ADP pathway involved in the binding of fibrinogen.
- Alkalating agent - testicular - bladder - ovary -& lung - Nephrotoxicity & CN VIII damage.

7. What are three possible toxicities of NSAID usage?
Severe Gram - rod infections.
It would increase to ~ 100 beats/min. Both sympathetic and vagal stimulation would be knocked out - but the SA node has an intrinsic pace of 100 beats/min - Which is normally checked by vagal stimulation.
1. Renal damage 2. Aplastic anemia 3. GI distress
Recurrent UTIs - Shigella - Salmonella - Pneumocystis carinii pneumonia

8. Explain pH dependent urinary drug elimination?
Tendonitis and Tendon rupture
The COX-2 inhibitors should not have the corrosive effects of other NSAIDs on the gastrointestinal lining.
In 4 half - lifes= (94%) T1/2 = (0.7x Vd)/CL
- Weak Acids>Alkinalize urine(CO3) to remove more - Weak bases>acidify urine to remove more

9. What are the major structural differences between Penicillin and Cephalosporin?
Cephalosporin: 1) has a 6 member ring attached to the Beta lactam instead of a 5 member ring 2)has an extra functional group ( attached to the 6 member ring)
Inhibits organification and coupling of thyroid hormone synthesis. Also decreases peripheral conversion of T4 to T3.
- Oxalic acid - Acidosis & nephrotoxicity
WEPT: Warfarin affects the Extrinsic pathway and prolongs the PT.

10. Mannitol - mechanism?
IV vitamin K and fresh frozen plasma
As an anticholinesterase it increases endogenous ACh and thus increases strength.
1. Heavy bleeding 2. GI effects (n/v - anorexia) 3. Abdominal pain
osmotic diuretic - increase tubular fluid osmolarity - thereby increasing urine flow

11. How are Interferons (INF) used clinically?

12. Which drug(s) cause this reaction: Anaphylaxis?
Misoprostol is a PGE1 analog that increases the production and secretion of the gastic mucous barrier.
acts at the proximal convoluted tubule to inhibit carbonic anhydrase. Causes self - limited sodium bicarb diuresis and reduction of total body bicarb stores.
Cell membrane Ca2+ channels of cardiac sarcomere
- Penicillin

13. Adverse effects of Guanethidine?
increased AP duration - increased ERP increased QT interval. Atrial and ventricular.
- Flumazenil
Same as penicillin. Extended spectrum antibiotics
orthostatic and exercise hypotension - sexual dysfunction - diarrhea

14. Why would a patient with cog - wheel rigidity and a shuffling gait be given benztropine?
Parkinson patients benefit from antimuscarinic agents through its inhibitory action within the indirect pathway.
Dermatophytes (tinea - ringworm)
Anaerobes
Hemolysis (if G6PD deficient) - Neurotoxicity - Hepatotoxicity - SLE- like syndrome

15. What is Imipenem always administered with?
They activate the ciliary muscle of the eye (open angle) and pupillary sphincter (narrow angle).
Cilastatin
Penicillin - G
vascular sm. Mus.: Nifedipine>Diltiazem>Verapamil

16. Which RT inhibitor causes Megaloblastic Anemia?
Prevents the release of Ca from SR of skeletal muscle
- Cloazapine - carbamazapine - colchicine - PTU
AZT
Bactericidal for: Gram + rod and cocci - Gram - cocci - and Spirochetes

17. Why is Cilastatin administered with Imipenem?
Nitrates
To inhibit renal Dihydropeptidase I and decrease Imipenem inactivation in the renal tubules
Recurrent UTIs - Shigella - Salmonella - Pneumocystis carinii pneumonia
Hormone synthesis inhibition (Gynecomastia) - Liver dysfunction (Inhibits CYP450) - Fever - Chills

18. Ca2+ channel blockers - clinical use?
hypertension - angina - arrhythmias
Quinidine - Amiodarone - Procainamide - Disopyramide
Modification via Acetylation - Adenylation - or Phosphorylation
- Metronidazole - certain cephalosporins - procarbazine - sulfonylureas

19. Adverse effects of Hydralazine?
nausea - headache - lupus - like syndrome - reflex tachycardia - angina - salt retention
Heparin catalyzes the activation of antithrombin III.
Hypersensitivity reactions
pulmonary fibrosis - corneal deposits - hepatotoxicity - skin deposits resulting in photodermatitis - neurologic effects - consitpation - CV (bradycardia - heart block - CHF) - and hypo - or hyperthyroidism.

20. What is the category of drug names ending in - azepam (e.g. Diazepam)
- Ethanol - dialysis - & fomepizole
Mg = Must go to the bathroom.
Immediate anticoagulation for PE - stroke - angina - MI - DVT.
Benzodiazepine.

21. How is Amphotericin B administered for fungal meningitis?
Inhibits bacterial Dihydrofolate Reductase - Bacteriostatic
Intrathecally
The COX-2 inhibitors should not have the corrosive effects of other NSAIDs on the gastrointestinal lining.
Acts as a wide spectrum carbapenem

22. What are two toxicities associated with Cyclosporine?
Methicillin - Nafcillin - and Dicloxacillin
1. Addison's disease 2. Inflammation 3. Immune suppression 4. Asthma
1. Predisposes to viral infections and lymphoma 2. Nephrotoxic (preventable with mannitol diuresis)
1. Tolbutamide 2. Chlorpropamide 3. Glyburide 4. Glipizide

23. What is the MOA for Clindamycin?
- Fluoroquinolones
Methylxanthine.
Cryptococcal meningitis in AIDS patients and Candidal infections of all types
Blocks Peptide Bond formation at the 50S subunit - Bacteriostatic

24. Loop diuretics (furosemide)- site of action?
osmotic diuretic - increase tubular fluid osmolarity - thereby increasing urine flow
thick ascending limb
all except the K+ sparing diuretics Spironolactone - Triamterene - Amiloride
- Methotrexate - 5 FU - 6 mercaptopurine

25. What is the effect of guanethidine on adrenergic NE release?
As PABA antimetabolites that inhibit Dihydropteroate Synthase - Bacteriostatic
It inhibits release of NE.
Does not cross
Resistant Gram - infections

26. What is the mechanism of action of the Alpha - glucosidase inhibitors?
Inhibit intestinal bursh border Alpha - glucosidases; delayed hydrolysis of sugars and absorption of sugars leading to decresed postprandial hyperglycemia.
- Class III antiarrhythmics (sotalol) - class IA (quinidine)
Interstitial nephritis
Constant FRACTION eliminated per unit time.(exponential)

27. Acetazolamide - clinical uses?
glaucoma - urinary alkalinization - metabolic alkalosis - altitude sickness
Prevents the release of Ca from SR of skeletal muscle
Cilastatin
sedation - positive Coombs' test

28. How is Ganciclovir activated?
Sotalol - Ibutilide - Bretylium - Amiodarone
Phosphorylation by a Viral Kinase
1. Tolbutamide 2. Chlorpropamide 3. Glyburide 4. Glipizide
Protamine sulfate

29. What conditions would you use dantrolene?
In treatment of malignant hyperthermia - due to concomitant use of halothane and succinylcholine. Also in neuroleptic malignant syndrome - a toxicity of antipsychotic drugs.
Succinylcholine
No - warfarin - unlike heparin - can cross the placenta.
proarrhythmic

30. List the specific antidote for this toxin: Tricyclic antidepressants
WEPT: Warfarin affects the Extrinsic pathway and prolongs the PT.
Erythromycin - Azithromycin - Clarithromycin
Inhibits DNA dependent RNA polymerase
- NaHCO3

31. Which drug(s) cause this reaction: Fanconi's syndrome?
- Glucocorticoid withdrawal
Only in limited amounts
- Class III antiarrhythmics (sotalol) - class IA (quinidine)
- Tetracycline

32. Describe Phase I metabolism in liver(3)?
1. Pioglitazone 2. Rosiglitazone.
Norepinephrine
Beta 2 agonist; used as a long - acting agent for prophylaxis. Adverse effects are tremor and arrhythmia.
- reduction - oxy - & hydrolysis - H2O sol. Polar product - P450

33. What additional side effects exist for Ampicillin?
Rash - Pseudomembranous colitis
The COX-2 inhibitors should not have the corrosive effects of other NSAIDs on the gastrointestinal lining.
Treatment of hypertension - especially with renal disease (lowers bp centrally - so flow is maintained to kidney).
Binds ergosterol - Disrupts fungal membranes

34. Antiarrhythmic Class III- effects?
Inhibit Ergosterol synthesis
increase AP duration - increase ERP - increase QT interval - for use When other arrhythmics fail
Zidovudine (AZT) - Didanosine (ddI) - Zalcitabine (ddC) - Stavudine (d4T) - Lamivudine (3TC)
Aminoglycosides

35. What parasites are treated with Pyrantel Pamoate (more specific)?
Blood
Rifampin - Ethambutol - Streptomycin - Pyrazinamide - Isoniazid (INH)
reduce levels of Angiotensin II - thereby preventing the inactivation of bradykinin (a potent vasodilator); renin level is increased
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)

36. What are the clinical uses for Aztreonam?
Slow - limited by half lives of clotting factors
Gram - rods: Klebsiella species - Pseudomonas species - Serratia species
ARF - shock - drug overdose - decrease intracranial/intraocular pressure
1. Buffalo hump 2. Moon facies 3. Truncal obesity 4. Muscle wasting 5. Thin skin 6. Easy bruisability 7. Osteoporosis 8. Adrenocortical atrophy 9. Peptic ulcers

37. What is the clinical use for Penicillin?
The PT.
Bactericidal for: Gram + rod and cocci - Gram - cocci - and Spirochetes
Interferes with microtubule function - disrupts mitosis - inhibits growth
Inhibits Viral DNA polymerase

38. What is a Ribavirin toxicity?
Corticosteroids; prevent production of leukotrienes from arachodonic acid by blocking phospholipase A2. Drugs of choice in a patient with status asthmaticus (in combination with albuterol.)
Cardiac glycoside (inotropic agent).
- Ethanol - dialysis - & fomepizole
Hemolytic anemia

39. What enzyme is responsible for the degredation of Ach
Activates cholinergic receptors on bladder and bowel smooth muscle - alleviating post - op and neurogenic ileus and urinary retention.
- Constant AMOUNT eliminated per unit time. - Etoh & ASA
Aminoglycosides
Acetylcholine esterase

40. What are the clinical uses for 1st Generation Cephalosporins?
Blastomyces - Coccidioides - Histoplasma - C. albicans; Hypercortisolism
Gram + cocci - Proteus mirabilis - E. coli - Klebsiella pneumoniae (PEcK)
Penicillin - Ampicillin - Ticarcillin - Pipercillin - Imipenem - Aztreonam - Cephalosporins
penicillinase resistant

41. Hydrochlorothiazide - clinical use?
Foscarnet = pyroFosphate analog
Diarrhea
HTN - CHF - calcium stone formation - nephrogenic DI.
Beta 2 agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Use during acute exacerbation.

42. Mannitol - clinical use?
Scopolamine
Disulfiram - like reaction with EtOH - Headache
ARF - shock - drug overdose - decrease intracranial/intraocular pressure
AZT - to reduce risk of Fetal Transmission

43. Name some common Sulfonamides (4)
Aplastic anemia (dose independent) - Gray Baby Syndrome
Ataxia - Dizziness - Slurred speech
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine
DHPG (dihydroxy-2- propoxymethyl guanine)

44. Acetazolamide - toxicity?
Prevents the release of Ca from SR of skeletal muscle
Impairs the synthesis of vitamin K- dependent clotting factors
hyperchloremic metabolic acidosis - neuropathy - NH3 toxicity - sulfa allergy
Cestode/tapeworm (e.g. - D. latum - Taenia species Except Cysticercosis

45. List the mechanism - clinical use - & toxicity of Etoposide.
1. Aluminum hydroxide: constipation and hypophosphatemia 2. Magnesium hydroxide: diarrhea 3. Calcium carbonate: Hypercalcemia - rebound acid increase - All may cause hypokalemia
Oral
- Topo II inhibitor(GII specific) - Oat cell of Lung & prostate - & testicular - Myelosuppression & GI irritation.
hyperkalemia - endocrine effects (gynecomastia - anti - androgen)

46. What is the formula for Clearance (CL)
Praziquantel
Inhibits DNA dependent RNA polymerase
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.
CL= (rate of elimination of drug/ Plasma drug conc.)

47. Adverse effects of Hydrochlorothiazide?
- Clindamycin
1) Serious Gram - infections resistant to other Beta lactams 2) Meningitis (most penetrate the BBB)
hypokalemia - slight hyperlipidemia - hyperuricemia - lassitude - hypercalcemia - hyperglycemia
hyperchloremic metabolic acidosis - neuropathy - NH3 toxicity - sulfa allergy

48. Is resistant to penicillinase?
Treatment of hypertension - especially with renal disease (lowers bp centrally - so flow is maintained to kidney).
Imipenem
Modification via Acetylation
increased AP duration - increased ERP increased QT interval. Atrial and ventricular.

49. List the mechanism - clinical use - & toxicity of 6 MP.
- inhibits HGPRT (pur. Syn.) - Luk - Lymph
Bind cell membrane - disrupt osmotic properties - Are Cationc - Basic and act as detergents
decrease conduction velocity - increase ERP - increase PR interval
Beta1 more than B2

50. The COX-2 inhibitors (celecoxib - rofecoxib) have similar side effects to the NSAIDs with What one exception?
- Alkalate DNA - Brain tumors - CNS toxicity
1. Suppresses organ rejection after transplantation 2. Selected autoimmune disorders.
-100% oxygen - hyperbaric
The COX-2 inhibitors should not have the corrosive effects of other NSAIDs on the gastrointestinal lining.