USMLE Step 1 Review -Pharmacology

USMLE Step 1 Review -Pharmacology
please select the one correct answer

1. A 19 yo with no symptoms had this ECG before a work out. He did have abnormal palpitations a year ago but required no therapy. He was not given any medical therapy but did try some over the counter herbal medications. His ECG is shown here. hb-11 . He most likely has?

a.first degree HB
b.atrial flutter
c.Normal sinus rhythm
d.atrial fibrillation
e.ventricular arrhythmia
f.Torsades de pointes

First degree heart block is fairly common. It can sometimes be found in teenagers, young adults and in well-trained athletes. The condition may be caused by rheumatic fever, some types of heart disease and by some drugs. First-degree heart block causes no symptoms. When the PR interval is > 0.2 ms, the diagnosis of first degree HB is made. This type of HB is fairly common in young teenagers and in athletes. It can be caused by congenital heart disease and some drugs like digoxin. The disorder is asymptomatic and requires no treatment. C

2. A 43 yo with mitral stenosis is found to have a dilated left atrium. She is asymptomatic and had a BP of 90/50. You are unable to feel her pulse. The chest x ray reveals a large heart. As a precaution, your chief resident decides to place her on warfarin. Of all the below ECG rhythms, she most likely has?

a. atrial flutter
b. premature atrial beats
c. first degree heart block
d. atrial fibrillation
e. ventricular tachycardia
f. sinus tachycardia

Atrial fibrillation is common with advancing age; however other causes include uncontrolled hypertension, coronary disease, CHF, valvular heart disease, acute pulmonary processes, hyperthyroidism, and acute alcohol intoxication. Patients having undergone cardiac, pulmonary, or esophageal surgery have a 20-40% postoperative incidence of atrial fibrillation (AF). Patients with congenital heart disease are at higher risk for developing AF. The most common arrhythmia seen in patients with mitral stenosis is atrial fibrillation. The dilated atrium also has a tendency to form a clot which frequently embolizes. D

3. The most common type of immune deficiency in children is?
a. AIDs
b. DiGeorge
c. Selective IgA
d. SCID
e. CGD

The most common congenital immune deficiency is selective IgA. There also exists selective IgM and IgG deficiencies, but they are less common. IgA deficiency may be due to a failure of heavy-chain gene switching. C

4. Deficiency of the enzyme adenosine deaminase (in RBCs) is seen in?
a. AIDs
b. SCIDs
c. DiGeorge
d. CGD
e. Jobs

Autosomal Recessive. Adenosine Deaminase deficiency leads to accumulation of dATP. This leads to a decrease in DNA precursors molecules. Severe deficiency in both humoral and cellular immunity occurs due to impaired DNA synthesis. Bone marrow transplant may be helpful in treatment. B

5. Fibrinolytic therapy can be used in all medical disorders except:

a. a recent hemorrhagic brain injury
b. recent head trauma
c. closed head or facial injury
d. presence of a brain tumor
e. presence of a brain AV malformation or a hemangioma
f. presence of an aortic dissection
g. embolic occlusion of the femoral artery
h. DIC
i. Active GI bleed

Fibrinolytic therapy should never be used if there in any condition where bleeding has occurred or can occur. The majority of embolic occlusions of arteries are from blood clots. In such cases, fibrinolytic therapy can be used to dissolve the blood clot. G

6. After starting a patient on a heparin drip for a pulmonary embolus, the earliest time to monitor the first set of PTT is:

a. 4-6 hrs
b. 12 hrs
c. 24 hrs
d. 1 hr
e. 4 hrs

After starting Heparin, the PTT is monitored every 4-6 hrs for the first 24 hours. When the PTT is therapeutic between 55-70 s, the PTT can be monitored on a daily basis. A

7. The lytic agent which acts directly on plasminogen is:

a.Streptokinase
b.Urokinase
c.Hirudin
d.Warfarin
e.Heparin
f.Plavix
g.Ticlodipine
h.Aspirin

Urokinase is a serine protease which acts directly on plasminogen. Urokinase is also found in physiological amounts in the blood and prostate. It has the ability to directly act on plasminogen and breaking it into plasmin. The activated plasmin then breakdowns the blood clot or thrombin. A

8. A 49 year old female is admitted with pain her left calf. You suspect she may have a DVT and order a Doppler ultrasound. The test indicates that she has a 3 cm blood clot in the proximal popliteal vein. You decide to start her on an anti coagulant. Which is false about Heparin?

a. It is a mucopolysaccharide
b. It is often administered two – three times daily
c. It binds to anti-thrombin 111 for its mode of action
d. It can be used as an oral dose when treating DVT
e. A PTT times should be monitored in patients receiving Heparin
f. It occurs naturally in the body

Heparin is a mucopolysaccharide, which is normally found in the basophils and mast cells. It acts as an anti coagulant and helps prevent the formation of blood clots. Unlike fibrinolytics, heparin does not break down the already formed clots. Heparin is used to treat a variety of medical disorders including acute myocardial infarction, atrial fibrillation, deep vein thrombosis, pulmonary embolism; Heparin can never be used as an oral agent and is ether administered subcutaneously or intravenously. Its activity needs to be monitored by measuring PTT levels. D

9. The following patient is started on heparin. During the 3rd day, you are asked which of the following is not a complication of Heparin therapy.

a.Thrombocytopenia
b.osteoporosis
c.alopecia
d.urticaria
e.skin necrosis

Heparin is generally a safe drug but does have a few side effects. The most serious is heparin induced thrombocytopenia (HIT) which presents with occlusion of the arteries. The heparin should be stopped immediately and the platelet count should be monitored. The condition can be reversed and heparin use should be avoided. Other rare side effects of heparin include osteoporosis, alopecia, uritcaria, skin necrosis commonly occurs with Warfarin. E

10. Which of the anti coagulants has been associated with skin necrosis?

a. aspirin
b. Ticlodipine
c. Warfarin
d. Urokinase
e. streptokinase

Rarely, Warfarin has been known to cause a severe type of skin necrosis. This adverse side effect generally tends to occur early after initiation of treatment and has been linked to protein C or S deficiency. Protein C is an innate anticoagulant that, like the procoagulant factors that Warfarin inhibits, requires vitamin K-dependent carboxylation for its activity. Since Warfarin initially decreases protein C levels faster than the coagulation factors, it can paradoxically increase the blood's tendency to coagulate when treatment is first begun. This is the reason why many patients are fist given heparin prior to starting Warfarin. Occasionally, large blood clots may form all over the body, esp. the extremities. C