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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. Aztreonam is not ________ with penicillins
viral kinase
With supplemental Folic Acid
- Infections - Trauma - Seizures - CO - Overdose - Metabolic - Alcohol (IT'S COMA)
cross - allergenic

2. Beta Blockers - site of action?
very short acting
Imipenem
Beta adrenergic receptors and Ca2+ channels (stimulatory)
penicillinase resistant

3. What are three possible complications of Heparin therapy?
constipation - flushing - edema - CV effects (CHF - AV block - sinus node depression) - and torsade de pointes (Bepridil)
Beta antagonist.
1. Bleeding 2. Thrombocytopenia 3. Drug - drug interactions
1. Aluminum hydroxide: constipation and hypophosphatemia 2. Magnesium hydroxide: diarrhea 3. Calcium carbonate: Hypercalcemia - rebound acid increase - All may cause hypokalemia

4. Which drug(s) cause this reaction: Torsade de pointes (2)?
Early myocardial infarction.
- Class III antiarrhythmics (sotalol) - class IA (quinidine)
Slow - limited by half lives of clotting factors
Inhalational general anesthetic.

5. What additional side effects exist for Ampicillin?
1. Hypoglycemia (more common with 2nd - generation drugs: glyburide - glipizide) 2. Disulfiram - like effects (not seen with 2nd - generation drugs).
Paranteral (IV - SC)
1. Significant: nephrotoxicity 2. Peripheral neuropathy 3. Hypertension 4. Pleural effusion 5. Hyperglycemia.
Rash - Pseudomembranous colitis

6. Which cancer drugs work at the level of mRNA(2)?
- Steroids - Tamoxifen
Sulfamethoxazole (SMZ) - Sulfisoxazole - Triple sulfas - Sulfadiazine
Hemicholinium inhibits the transport of choline into the nerve - thus inhibiting formation of ACh.
Early myocardial infarction.

7. Why is Cilastatin administered with Imipenem?
very short acting
To inhibit renal Dihydropeptidase I and decrease Imipenem inactivation in the renal tubules
Beta antagonist.
Misoprostol is contraindicated in women of childbearing potential because it is an abortifacient.

8. What is a mnemonic to remember Amantadine's function?
Blocks Influenza A and RubellA; causes problems with the cerebellA
not a sulfonamide - but action is the same as furosemide
Same as penicillin. Act as narrow spectrum antibiotics
torsade de pointes

9. Ca2+ channel blockers - toxicity?
Close K+ channels in Beta - cell membrane leading to cell depolarization causing insulin release triggered by increase in Calcium ion influx.
Mycobacterium tuberculosis - the only agent used as solo prophylaxis against TB
- Lithium
cardiac depression - peripheral edema - flushing - dizziness - constipation

10. What are four conditions in Which H2 Blockers are used clinically?
- Fluoroquinolones
decrease the slope of phase 4 - increase PR interval (the AV node is particularly sensitive)
- acetylation - glucuron. - & sulfation - Conjugation - Polar product
1. Peptic ulcer 2. Gastritis 3. Esophageal reflux 4. Zollinger - Ellison syndrome

11. Antiarrhythmic class IV- clinical use?
H2 antagonist
- Isoniazid
prevention of nodal arrhythmias (SVT)
AV nodal cells

12. What is the mechanism of action and clinical use of the antiandrogens Ketoconazole and Spironolactone?
Inhibit steroid synthesis - used in the treatment of polycystic ovarian syndrome to prevent hirsutism.
Digitoxin 168hrs Digoxin 40 hrs
glaucoma - urinary alkalinization - metabolic alkalosis - altitude sickness
1. Predisposes to viral infections and lymphoma 2. Nephrotoxic (preventable with mannitol diuresis)

13. List some specifics of lead poisoning(4)?
Hemolysis (if G6PD deficient) - Neurotoxicity - Hepatotoxicity - SLE- like syndrome
diuretics - sympathoplegics - vasodilators - ACE inhibitors - Angiotensin II receptor inhibitors
Dobutamine has more of an affintiy for beta -1 than beta -2 - and is used for treating heart failure and shock. Albuterol and terbutaline is the reverse - and is used in treatment of acute asthma.
- A57Blue lines in gingiva & long bones - Encephalopathy & Foot drop - Abdominal colic / - Sideroblastic anemia

14. Which of epi - norepi - or isoproterenol results in bradycardia?
Sulfonylureas are oral hypoglycemic agents - they are used to stimulate release of endogenous insulin in NIDDM (type -2).
Acts as a wide spectrum carbapenem
In treatment of malignant hyperthermia - due to concomitant use of halothane and succinylcholine. Also in neuroleptic malignant syndrome - a toxicity of antipsychotic drugs.
Norepinephrine

15. What is the lab value used to monitor the effectiveness of Warfarin therapy?
The PT.
- Barbiturates - phenytoin - carbamazipine - rifampin - griseofulvin - quinidine
NE acts presynaptically on alpha -2 receptors to inhibit its own release. ACh also acts presynaptically through M1 receptors to inhibit NE release.
- DNA intercalator - Hodgkin's - myeloma - sarcoma - and solid tumors - Cardiotoxicity & alopecia

16. What is are two clinical uses of Cyclosporine?
1. Suppresses organ rejection after transplantation 2. Selected autoimmune disorders.
Gemfibrozil - Clofibrate
Inhibit intestinal bursh border Alpha - glucosidases; delayed hydrolysis of sugars and absorption of sugars leading to decresed postprandial hyperglycemia.
Tendonitis and Tendon rupture

17. What is the category of drug names ending in - barbital (e.g. Phenobarbital)
Babiturate.
1) Serious Gram - infections resistant to other Beta lactams 2) Meningitis (most penetrate the BBB)
- DNA intercalator - testicular & lymphomas - Pulmonary fibrosis mild myelosuppression.
Used in combination therapy with SMZ to sequentially block folate synthesis

18. Resistance mechanisms for Chloramphenicol
Atropine pts are suffering from Cholinestrase inhibitor poisining (Nerve gas/Organophosphate poisining)
Chronic gout.
Modification via Acetylation
Headache - flushing - dyspepsia - blue - green color vision.

19. What are two toxicities of the Glitazones?
GI discomfort - Acute cholestatic hepatitis - Eosinophilia - Skin rashes
No - hemicholinum block the uptake of Choline and thus Ach synthesis
1. Weight gain 2. Hepatotoxicity (troglitazone)
Benzodiazepine.

20. Which diuretics increase urine K+?
Small lipid - soluble molecule
- Hypersensitivity reactions - Hemolysis - Nephrotoxicity (tubulointerstitial nephritis) - Kernicterus in infants Displace other drugs from albumin (e.g. - warfarin)
all except the K+ sparing diuretics Spironolactone - Triamterene - Amiloride
- Upper respiratory tract infections - pneumonias - STDs: Gram+ cocci (streptococcal infect in pts allergic to penicillin) - Mycoplasma - Legionella - Chlamydia - Neisseria

21. Why are the Sulfonylureas inactive in IDDM (type -1)?
Chloramphenicol - Erythromycin/macrolides - Lincomycin - Clindamycin - Streptogramins (quinupristin - dalfopristin)
Because they require some residual islet function.
- Hypersensitivity reactions - Hemolysis - Nephrotoxicity (tubulointerstitial nephritis) - Kernicterus in infants Displace other drugs from albumin (e.g. - warfarin)
Decrease the production of leukotrienes and protaglandins by inhibiting phospholipase A2 and expression of COX-2.

22. List the specific antidote for this toxin: Carbon monoxide
- Tricyclic antidepressants
- MT polymerization inhibitor(M phase) - MOPP - lymphoma - Willm's & choriocarcinoma - neurotoxicity and myelosuppression
-100% oxygen - hyperbaric
- Weak Acids>Alkinalize urine(CO3) to remove more - Weak bases>acidify urine to remove more

23. Digoxin v. Digitoxin: bioavailability?
Enterobacter
Digitoxin>95% Digoxin 75%
physostigmine
- Chloramphenicol

24. What process does Zafirlukast interfere with?
Hypersensitivity reactions
Rifampin - Ethambutol - Streptomycin - Pyrazinamide - Isoniazid (INH)
Leukotrienes increasing bronchial tone.
IV vitamin K and fresh frozen plasma

25. How are the HIV drugs used clinically?

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26. What is the memory key for the effect of aluminum hydroxide overuse?
Increase target cell response to insulin.
toxic
AluMINIMUM amount of feces.
The PTT.

27. What is the formula for Clearance (CL)
1. Peptic ulcer 2. Gastritis 3. Esophageal reflux 4. Zollinger - Ellison syndrome
VACUUM your Bed Room'
CL= (rate of elimination of drug/ Plasma drug conc.)
Gram + cocci - Proteus mirabilis - E. coli - Klebsiella pneumoniae (PEcK)

28. In coma situations you rule out What (7)?

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29. Why would dopamine be useful in treating shock?
Pregnant women - Children; because animal studies show Damage to Cartilage
Receptors = D1=D2>beta>alpha - thus increasing heart rate (beta) and blood pressure (alpha vasoconstriction) while maintaining kidney perfusion (dopamine receptors)
Aminoglycosides
Competitive inibitor of progestins at progesterone receptors.

30. What organisms does Griseofulvin target?
aPTT (intrinsic pathway)
decrease the slope of phase 4 - increase PR interval (the AV node is particularly sensitive)
Dermatophytes (tinea - ringworm)
is resistant

31. List the specific antidote for this toxin: Tricyclic antidepressants
1. Antipyretic 2. Analgesic 3. Anti - inflammatory
- NaHCO3
Ototoxicity - Hypokalemia - Dehydration - Allergy (sulfa) - Nephritis (interstitial) - Gout
prevention of nodal arrhythmias (SVT)

32. Resistance mechanisms for Sulfonamides
Finasteride inhibits 5 Alpha - reductase - this decreases the conversion of testosterone to dihydrotestosterone - useful in BPH
Enterobacter
Acetylates and irreversibly inhibits cyclooxygenase (COX I and COX II) to prevent the conversion of arachidonic acid to prostaglandins.
Altered bacterial Dihydropteroate Synthetase - Decreased uptake - or Increased PABA synthesis

33. What is Nifurtimox administered for?

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34. Why would a patient with cog - wheel rigidity and a shuffling gait be given benztropine?
Spironolactone - Triamterene - Amiloride (the K+ STAys)
alpha -1 > alpha -2; used as a pupil dilator - vasoconstrictor - and for nasal decongestion
Parkinson patients benefit from antimuscarinic agents through its inhibitory action within the indirect pathway.
1. Mycobacterium tuberculosis 2. Delays resistance to Dapsone When used of Leprosy 3. Used in combination with other drugs

35. Why is pyridostigmine effective in the treatment of myasthenia gravis?
Antiprotozoal: Giardia - Entamoeba - Trichomonas - Gardnerella vaginalis Anaerobes: Bacteroides - Clostridium
As an anticholinesterase it increases endogenous ACh and thus increases strength.
Inhibit Ergosterol synthesis
1. Antiandrogen 2. Nausea 3. Vomiting

36. Acetazolamide - toxicity?
Leukopenia - Neutropenia - Thrombocytopenia - Renal toxicity
BM suppression (neutropenia - anemia) - Peripheral neuropathy
hyperchloremic metabolic acidosis - neuropathy - NH3 toxicity - sulfa allergy
- Chloramphenicol

37. MOA of Succinylcholine
Prevents the release of Ca from SR of skeletal muscle
Nephrotoxicity
Acetylates and irreversibly inhibits cyclooxygenase (COX I and COX II) to prevent the conversion of arachidonic acid to prostaglandins.
1. Bleeding 2. Teratogenicity 3. Drug - drug interactions

38. How can the t1/2 of INH be altered?
Fast vs. Slow Acetylators
1. Gastric ulceration 2. Bleeding 3. Hyperventilation 4. Reye's syndrome 5. Tinnitus (CN VIII)
Can affect absorption - bioavailability - or urinary excretion of other drugs by altering gastric and urinary pH or by delaying gastric emptying.
Imipenem

39. Adverse effects of Hydralazine?
nausea - headache - lupus - like syndrome - reflex tachycardia - angina - salt retention
Verapamil - Diltiazem - Bepridil
Due to the presence of a bulkier R group
Digitoxin>95% Digoxin 75%

40. Name three Antiarrhythmic drugs in class IB.
Inhibits platelet aggregation by irreversibly inhibiting the ADP pathway involved in the binding of fibrinogen.
Rifampin
No. Atropine is used to reduce urgency in mild cystitis. So it would aggravate the urinary retention.
Lidocaine - Mexiletine - Tocainide

41. Which drug(s) cause this reaction: Disulfram - like reaction (4) ?
- Metronidazole - certain cephalosporins - procarbazine - sulfonylureas
1. Meningococcal carrier state 2. Chemoprophylaxis in contacts of children with H. influenzae type B
- Disulfram & also sulfonylureas - metronidazole
DHPG (dihydroxy-2- propoxymethyl guanine)

42. What are common side effects of Amphotericin B?
Rare.
Fever/Chills - Hypotension - Nephrotoxicity - Arrhythmias
- inhibits HGPRT (pur. Syn.) - Luk - Lymph
Abortifacient.

43. What is the category of drug names ending in - phylline (e.g. Theophylline)
Protease inhibitor.
distal convoluted tubule (early)
Headache - flushing - dyspepsia - blue - green color vision.
Methylxanthine.

44. What is the mechanism of action of Mifepristone (RU486)?
- MT polymerization inhibitor(M phase) - MOPP - lymphoma - Willm's & choriocarcinoma - neurotoxicity and myelosuppression
Inhibits cGMP phosphodiesterase - casuing increased cGMP - smooth muscle relaxation in the corpus cavernosum - increased blood flow - and penile erection.
Competitive inibitor of progestins at progesterone receptors.
Intrathecally

45. List the mechanism - clinical use - & toxicity of Cyclophosphamide.
To inhibit renal Dihydropeptidase I and decrease Imipenem inactivation in the renal tubules
Due to the presence of a bulkier R group
Epinephrine
- Alkalating agent - NHL - Breast - ovary - & lung. - Myelosuppression - & hemorrhagic cystitis.

46. Which drug(s) cause this reaction: Tendonitis and rupture?
Hydralazine and Minoxidil
- Fluoroquinolones
hyperkalemia - endocrine effects (gynecomastia - anti - androgen)
- Chlorpromazine - thioridazine - haloperidol

47. What is the category - desired effect - and period of use of albuterol in the treatment of Asthma?
Beta 2 agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Use during acute exacerbation.
Cilastatin
Antifungal.
Severe Gram - rod infections.

48. List the mechanism - clinical use - & toxicity of Paclitaxel.
- Chloramphenicol
- MT polymerization stabilizer - Ovarian & breast CA - Myelosupperession & hypersensitivity.
Competitive inibitor of progestins at progesterone receptors.
penicillinase resistant

49. Which drug(s) cause this reaction: Anaphylaxis?
- Antipsychotics
cyanide toxicity (releases CN)
- Penicillin
Rifampin (DOC) - minocycline

50. List the mechanism - clinical use - & toxicity of Nitrosureas.
- Alkalate DNA - Brain tumors - CNS toxicity
Ibuprofen - Naproxen - and Indomethacin
- Alkalating agents+cisplatin - Doxorubicin+Dactinomycin - Bleomycin - Etoposide
Cryptococcal meningitis in AIDS patients and Candidal infections of all types