Review of Pharmacology - 9E (2015)

Review of Pharmacology
36. Ans. (d) Serum TSH level (See below)
• TSH levels are elevated in a hypothyroid patient (because feedback inhibition by thyroid hormones is not present).
• Administration of thyroid hormones (T 3
and T 4
) decreases TSH by contributing to feedback inhibition.
• If TSH levels are less than normal, it signifies overtreatment whereas high TSH level suggests inadequate treatment.
37. Ans. (b) Reserpine (Ref: Katzung 11/e p677, CMDT-2010/1015)
Thyroid storm is an extreme form of thyrotoxicosis. The drugs used in thyroid storm are:
• Propanolol to control severe cardiovascular manifestations.
• Calcium channel blockers like diltiazem are used if b-blockers are contra-indicated as in asthmatics.
• Iodides (NaI, KI, Lugol’s iodine) to inhibit the release of thyroid hormones from the gland.
• Propylthiouracil or methimazole to reduce the synthesis of thyroid hormones.
• Hydrocortisone to protect the patient against shock.
Note: Aspirin should be avoided as it may displace T 4
from thyroid binding globulin resulting in elevated levels of free T 4
Endocrinology
38. Ans. (b) 8 hours (Ref: KDT 6/e p250)
Half-life of carbimazole is around 8 hours whereas propylthiouracil has t½ of 2 hours.
39. Ans. (d) Carbamazepine (Ref: Katzung 11/e p671-673)
40. Ans. (b) Cretinism (Ref: CMDT 2010/1005)
41. Ans. (d) Propylthiouracil (Ref: KDT 6/e p250)
42. Ans. (b) Captopril (Ref: KDT 6/e p484)
43. Ans. (a) Propylthiouracil (Ref KDT 6/e p250)
44. Ans. (c) Metformin (Ref: Goodman Gilman 12/e p1259)
• Lactic acidosis (more with phenformin) and megaloblastic anemia (more with metformin) due to vitamin B 12
deficiency
are the major adverse effects of these drugs. Lactic acidosis is more likely to occur in the presence of hepatic
and renal impairment or alcohol ingestion.
45. Ans. (a) Acarbose (Ref: Katzung 11/e p743-744)
Drugs that act by release of insulin can cause hypoglycemia. Therefore, glimepride (a sulfonylurea) and nateglinide that
blocks ATP sensitive potassium channels and release insulin will cause hypoglycemia as an advese effect whereas use of
acrabose alone is not associated with hypoglycemia.
46. Ans. (c) Glucose (Ref: Katzung 11/e p743-744)
• Complex carbohydrates (polysaccharides and sucrose) are absorbed after conversion to simple carbohydrates by
alpha-glucosidase. Inhibitors of this enzyme (acarbose and miglitol) decrease carbohydrate absorption from the GIT.
Although these drugs themselves do not cause hypoglycemia but blood sugar may decrease if these are combined
with insulin or other drugs releasing insulin. In such a case of hypoglycemia, simple carbohydrates like glucose (not
sucrose or other complex carbohydrates) should be used.
47. Ans. (c) It causes transcription of gene for carbohydrate and fat metabolism in the absence of insulin (Ref: Goodman and
Gilman 12/e p1260 , Katzung 12/e p758)
• Thiazolidinediones require the presence of insulin for pharmacological activity and are not indicated to treat
type 1 diabetes.
• Thiazolidinediones (glitazones) sensitize peripheral tissues to insulin. They bind a nuclear receptor called
peroxisome proliferator-activated receptor gamma (PPAR-gamma) and affect the expression of a number of
genes.
• Two drugs of this class, rosiglitazone and pioglitazone are available for clinical use. Rosiglitazone is primarily
metabolized by the CYP 2C8 isoenzyme and pioglitazone is metabolized by CYP 2C8 and CYP 3A4.
• Edema occurs in about 3–4% of patients receiving monotherapy with rosiglitazone or pioglitazone. The edema
occurs more frequently (10–15%) in patients receiving concomitant insulin therapy and may result in congestive
heart failure. The drugs are contraindicated in diabetic individuals with New York Heart Association
class III and IV cardiac status.
48. Ans. (b) It can be used for treatment of Type 1 diabetes mellitus (Ref: CMDT 2010 p1095)
• Exenatide (Exendin 4) is a GLP-1 receptor agonist that is more resistant to DPP-4 action and cleared by the kidney.
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