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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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1. Name several common Macrolides (3)
Penicillin.
Erythromycin - Azithromycin - Clarithromycin
- Penicillamine
Inhibit steroid synthesis - used in the treatment of polycystic ovarian syndrome to prevent hirsutism.

2. What is the receptor affinity and clinical use of isoproterenol?
1) Serious Gram - infections resistant to other Beta lactams 2) Meningitis (most penetrate the BBB)
Long.
It affects beta receptors equally and is used in AV heart block (rare).
1. Antipyretic 2. Analgesic 3. Anti - inflammatory

3. What is the memory key for the action of Sildenafil (Viagra)?
Sildenafil fills the penis
Hexamethonium is a nicotinic antagonist - and thus is a ganglionic blocker.
Blocks Peptide Bond formation at the 50S subunit - Bacteriostatic
toxic

4. What is the MOA of Polymyxins?
Selectively inhibit cyclooxygenase (COX) isoform 2 - Which is found in inflammatory cells nad mediates inflammation and pain; spares COX-1 Which helps maintain the gastric mucosa.
Hormone synthesis inhibition (Gynecomastia) - Liver dysfunction (Inhibits CYP450) - Fever - Chills
Penicillin.
Bind cell membrane - disrupt osmotic properties - Are Cationc - Basic and act as detergents

5. What are the major structural differences between Penicillin and Cephalosporin?
alpha -1 > alpha -2; used as a pupil dilator - vasoconstrictor - and for nasal decongestion
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)
impotence - exacerbation of asthma - CV effects - CNS effects - may mask hypoclycemia
osmotic diuretic - increase tubular fluid osmolarity - thereby increasing urine flow

6. What is the mechanism of action of Aspirin?
Competitive inibitor of progestins at progesterone receptors.
Prevents the release of ACh - Which results in muscle paralysis.
Inhibits cell wall mucopeptide formation - Bactericidal
Acetylates and irreversibly inhibits cyclooxygenase (COX I and COX II) to prevent the conversion of arachidonic acid to prostaglandins.

7. Steady state concentration is reached in __ number of half - lifes
Increased systolic and pulse pressure - decreased diastolic pressure - and little change in mean pressure.
Inhibit RT of HIV and prevent the incorporation of viral genome into the host DNA
In 4 half - lifes= (94%) T1/2 = (0.7x Vd)/CL
Polymyxins

8. Hydrochlorothiazide - mechanism?
Yes - it does not cross the placenta.
Inhibits NaCl reabsorption in the early distal tubule. Decreases Ca2+ excretion.
depresses ectopic pacemakers - especially in digoxin toxicity
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)

9. What are toxic side effects for Metronidazole?
- Formaldehyde & formic acid - severe acidosis & retinal damage
Disulfiram - like reaction with EtOH - Headache
troponin - tropomyosin system
- Atropine & pralidoxime

10. What is the mechanism of action of the Alpha - glucosidase inhibitors?
- Deferoxamine
Inhibit intestinal bursh border Alpha - glucosidases; delayed hydrolysis of sugars and absorption of sugars leading to decresed postprandial hyperglycemia.
Ceftriaxone
Inhibits cell wall synthesis ( binds to PBP3). A monobactam

11. Clinical use of Isoniazid (INH)?
Irreversibly inhibits H+/K+ ATPase in stomach parietal cells.
Zidovudine (AZT) - Didanosine (ddI) - Zalcitabine (ddC) - Stavudine (d4T) - Lamivudine (3TC)
When pts have Low CD4+ (< 500 cells/cubic mm) or a High Viral Load
Mycobacterium tuberculosis - the only agent used as solo prophylaxis against TB

12. Name two LPL stimulators.
Gemfibrozil - Clofibrate
Reversible block of histamine H2 receptors
- Vitamin K & fresh frozen plasma
Reversibly inhibits cyclooxygenase - mostly in CNS. Inactivated peripherally.

13. List the specific antidote for this toxin: Methemoglobin
torsade de pointes
- Methylene blue
Nonspecific beta - agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Adverse effect is tachycardia (Beta 1).
Gram + - Gram - - Norcardia - Chlamydia

14. Cocaine casues vasoconstriction and local anesthesia by What mechanism
depresses ectopic pacemakers - especially in digoxin toxicity
Indirect agonist - uptake inhibitor
Epinephrine
- Barbiturates - phenytoin - carbamazipine - rifampin - griseofulvin - quinidine

15. What is a mnemonic to remember Amantadine's function?
Large anionic polymer - acidic
AmOxicillin has greater Oral bioavailability
- S- phase anti - metabolite Pyr analogue - Colon - solid tumors - & BCC/ - Irreversible myelosuppression
Blocks Influenza A and RubellA; causes problems with the cerebellA

16. What parasites are treated with Pyrantel Pamoate (more specific)?
Cyclooxygenases (COX I - COX II).
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)
ARF - shock - drug overdose - decrease intracranial/intraocular pressure
Acts as a wide spectrum carbapenem

17. Toxic effects of TMP include?
Na/K ATPase
Megaloblastic anemia - Leukopenia - Granulocytopenia
vascular sm. Mus.: Nifedipine>Diltiazem>Verapamil
Chronic (weeks or months)

18. What are common side effects of RT Inhibitors?
hypertension - CHF - diabetic renal disease
Captopril - Enalapril - Lisinopril
Praziquantel
BM suppression (neutropenia - anemia) - Peripheral neuropathy

19. What is the category of drug names ending in - terol (e.g. Albuterol)
Beta -2 agonist.
Gram + cocci - Gram - rods - and Anerobes
all of them
Pyridoxine (B6) administration

20. List the mechanism - clinical use - & toxicity of Vincristine.

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21. What are five advantages of Oral Contraceptives (synthetic progestins - estrogen)?
Foscarnet = pyroFosphate analog
Sulfonamide Loop Diuretic. Inhibits ion co - transport system of thick ascending loop. Abolishes hypertonicity of the medulla - thereby preventing concentration of the urine.
1. Reliable (<1% failure) 2. Lowers risk of endometrial and ovarian cancer 3. Decreased incidence of ectopic pregnancy 4. Lower risk of pelvic infections 5. Regulation of menses
Used in combination therapy with SMZ to sequentially block folate synthesis

22. How is Ribavirin used clinically?
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
for RSV
Forms toxic metabolites in the bacterial cell - Bactericidal
PT

23. Which drug(s) cause this reaction: Hepatitis?
With supplemental Folic Acid
bradycardia - AV block - CHF
- Isoniazid
pulmonary fibrosis - corneal deposits - hepatotoxicity - skin deposits resulting in photodermatitis - neurologic effects - consitpation - CV (bradycardia - heart block - CHF) - and hypo - or hyperthyroidism.

24. If a patient is given hexamethonium - What would happen to his/her heart rate?
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.
Centrally acting alpha agonist - thus causing a decrease in central adrenergic outflow - spairing renal blood flow
- Tamoxifen
Penicillin - Ampicillin - Ticarcillin - Pipercillin - Imipenem - Aztreonam - Cephalosporins

25. ACE inhibitors - toxicity?
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.
fetal renal damage - hyperkalemia - Cough - Angioedema - Proteinuria - Taste changes - hypOtension - Pregnancy problems - Rash - Increased renin - Lower Angiotensin II (CAPTOPRIL)
Giant Roundworm (Ascaris) - Hookworm (Necator/Ancylostoma) - Pinworm (Enterobius)
increase AP duration - increase ERP - increase QT interval - for use When other arrhythmics fail

26. What is the mechanism of action of Cyclosporine?
Stimulating beta receptors stimulates heart rate - but beta receptor induced vasodilation reduces peripheral resistance.
Binds to cyclophilins (peptidyl proline cis - trans isomerase) - blocking the differentiation and activation of T cells mainly by inhibiting the production of IL-2 and its receptor.
DOC in diagnosing and abolishing AV nodal arrhythmias
Inhibits reabsorption of uric acid.

27. Which diuretics increase urine K+?
all except the K+ sparing diuretics Spironolactone - Triamterene - Amiloride
Bethanechol - Neostigmine - physostigmine
Nonspecific beta - agonist; desired effect is the relaxation of bronchial smooth muscle (Beta 2). Adverse effect is tachycardia (Beta 1).
Cephalosporins

28. Which drug(s) cause this reaction: Cardiac toxicity?
- Daunorubicin & Doxorubicin
Blocks translocation - binds to the 23S rRNA of the 50S subunit - Bacteriostatic
- Cloazapine - carbamazapine - colchicine - PTU
thiazides - amiloride

29. Which drug(s) cause this reaction: Adrenocortical Insufficiency
1. Reliable (<1% failure) 2. Lowers risk of endometrial and ovarian cancer 3. Decreased incidence of ectopic pregnancy 4. Lower risk of pelvic infections 5. Regulation of menses
- Glucocorticoid withdrawal
- DNA intercalator - Hodgkin's - myeloma - sarcoma - and solid tumors - Cardiotoxicity & alopecia
Ipratropium

30. Adverse effects of Clonidine?
Beta -2 agonist.
dry mouth - sedation - severe rebound hypertension
It inhibits release of NE.
1. Taken daily 2. No protection against STDs 3. Raises triglycerides 4. Depression - weight gain - nausea - HTN 5. Hypercoagulable state

31. What is the formula for Clearance (CL)
No
For serious - Gram + multidrug - resistant organisms
CL= (rate of elimination of drug/ Plasma drug conc.)
sedation - positive Coombs' test

32. What are two processes Corticosteroids inhibit leading to decreased inflammation?
Nifedipine - Verapamil - Diltiazem
Diuresis in pateints with sulfa allergy
1. In liver - increases storage of glucose as glycogen. 2. In muscle - stimulates glycogen and protein synthesis - and K+ uptake. 3. In adipose tissue - facilitates triglyceride storage.
1. Phospholipase A2 is prevented from releasing arachidonic acid 2. Decreases protein synthesis thus lowering amount of Cyclooxygenase enzymes

33. Resistance mechanisms for Vancomycin
Terminal D- ala of cell wall replaced with D- lac; Decreased affinity
acts at the proximal convoluted tubule to inhibit carbonic anhydrase. Causes self - limited sodium bicarb diuresis and reduction of total body bicarb stores.
BM suppression (neutropenia - anemia) - Peripheral neuropathy
fetal renal toxicity - hyperkalemia

34. What is the mechanism of action of Misoprostol?
TMP- SMZ
Activates antithrombin III
Misoprostol is a PGE1 analog that increases the production and secretion of the gastic mucous barrier.
1. Cimetadine 2. Ranitidine 3. Famotidine 4. Nizatidine

35. How is Vancomycin used clinically?
Pretreat with antihistamines and a slow infusion rate
For serious - Gram + multidrug - resistant organisms
To inhibit renal Dihydropeptidase I and decrease Imipenem inactivation in the renal tubules
hyperkalemia - endocrine effects (gynecomastia - anti - androgen)

36. List the specific antidote for this toxin: Warfarin
- Methylene blue
Prevents the release of Ca from SR of skeletal muscle
- Vitamin K & fresh frozen plasma
Acute gout.

37. Mannitol - mechanism?
Acute gout.
- N- acetylcystine
osmotic diuretic - increase tubular fluid osmolarity - thereby increasing urine flow
- Flumazenil

38. What enzyme does Zileuton inhibit?
distal convoluted tubule (early)
G6PD deficient individuals
Bleeding.
Lipoxygenase

39. List the specific antidote for this toxin: Anticholinesterases (organophosphate.)
- Atropine & pralidoxime
Ganciclovir is more toxic to host enzymes
severe hypertension - CHF
Edrophonium

40. What type of gout is treated with Probenacid?
1. Tolbutamide 2. Chlorpropamide 3. Glyburide 4. Glipizide
Phosphorylation by a Viral Kinase
Sulfonamides - Trimethoprim
Chronic gout.

41. List the specific antidote for this toxin: Beta Blockers
Inhibition of 50S peptidyl transferase - Bacteriostatic
- Glucagon
- Alkalates DNA - CML - Pulmonary fibrosis hyperpigmentation
Inhalational general anesthetic.

42. List the mechanism - clinical use - & toxicity of 6 MP.
Nephrotoxicity (esp. with Cephalosporins) - Ototoxicity (esp. with Loop Diuretics)
Foscarnet = pyroFosphate analog
- inhibits HGPRT (pur. Syn.) - Luk - Lymph
for RSV

43. Which drug(s) cause this reaction: Thrombotic complications?
Scopolamine
- Oral Contraceptives
narcolepsy - obesity - and attention deficit disorder (I wouldn't recommend this)
hypokalemia - slight hyperlipidemia - hyperuricemia - lassitude - hypercalcemia - hyperglycemia

44. Which Tetracycline is used in patients with renal failure? / Why?
Aluminum sucrose sulfate polymerizes in the acid environment of the stomach and selectively binds necrotic peptic ulcer tissue. Acts as a barrier to acid - pepsin - and bile.
sedation - depression - nasal stuffiness - diarrhea
Doxycycline - because it is fecally eliminated
Chronic Hepatitis A and B - Kaposi's Sarcoma

45. What organisms does Griseofulvin target?
Fast vs. Slow Acetylators
severe orthostatic hypotension - blurred vision - constipation - sexual dysfunction
Mycobacterium tuberculosis - the only agent used as solo prophylaxis against TB
Dermatophytes (tinea - ringworm)

46. Which drug(s) cause this reaction: Agranulocytosis (3)?
check PFTs - LFTs - and TFTs
Beta adrenergic receptors and Ca2+ channels (stimulatory)
Blood
- Cloazapine - carbamazapine - colchicine - PTU

47. Which individuals are predisposed to Sulfonamide - induced hemolysis?
Verapamil - Diltiazem - Bepridil
Dermatophytes (tinea - ringworm)
G6PD deficient individuals
Close K+ channels in Beta - cell membrane leading to cell depolarization causing insulin release triggered by increase in Calcium ion influx.

48. What are common toxicities associated with Tetracyclines?

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49. Which drug(s) cause this reaction: Extrapyramidal side effects (3)?
- Chlorpromazine - thioridazine - haloperidol
Reversibly inhibits cyclooxygenase - mostly in CNS. Inactivated peripherally.
Resistant Gram - infections
AluMINIMUM amount of feces.

50. What are the clinical indications for bethanechol?
Hemolytic anemia
Short.
Activates cholinergic receptors on bladder and bowel smooth muscle - alleviating post - op and neurogenic ileus and urinary retention.
cyanide toxicity (releases CN)