JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD Pharm. D III Year PHARMACOLOGY - II Previous Question Paper (June/July - 2022 - R08)

Anticoagulants are classified primarily into parenteral agents like heparin and oral agents like warfarin. Heparin acts by binding to antithrombin III, inducing a conformational change that accelerates the inactivation of thrombin (Factor IIa) and Factor Xa by 1000-fold. Warfarin acts as a vitamin K antagonist; it inhibits the enzyme vitamin K epoxide reductase (VKORC1), thereby preventing the gamma-carboxylation of glutamate residues on clotting factors II, VII, IX, and X, rendering them biologically inactive.

Adverse actions primarily involve bleeding complications, ranging from minor bruising to life-threatening intracranial hemorrhage. Heparin-induced thrombocytopenia (HIT) is a serious immune-mediated complication of heparin therapy. Warfarin can cause skin necrosis in patients with protein C deficiency and is strictly contraindicated in pregnancy due to teratogenicity.

Clinical manifestations of overdose or toxicity include hematuria, epistaxis, gingival bleeding, gastrointestinal hemorrhage, and ecchymosis. In severe cases, patients may present with hypotension and tachycardia due to acute blood loss. Management involves cessation of the drug and administration of specific antidotes: protamine sulfate for heparin and vitamin K or fresh frozen plasma for warfarin.

Plasma volume expanders are intravenous solutions used to restore intravascular volume in patients suffering from hypovolemic shock, severe hemorrhage, or burns. They are classified into crystalloids and colloids.

Crystalloids, such as Normal Saline (0.9% NaCl) and Ringer's Lactate, are inexpensive and isotonic, but they distribute rapidly into the interstitial space, requiring larger volumes. Colloids, such as Dextran, Hydroxyethyl Starch (HES), and Albumin, contain high-molecular-weight substances that remain in the intravascular compartment for longer periods due to their oncotic pressure, effectively drawing fluid from the interstitial space into the plasma. While colloids provide more sustained volume expansion, they carry risks of anaphylaxis and, in the case of HES, potential renal impairment.