Question

QUESTION 19

A comparatively large dose given at the beginning of treatment to quickly obtain therapeutic effects is called a:

		loading dose
		plateau
		half-life
		maintenance dose

QUESTION 20

Most drug metabolism is also referred to as:

		conjugation
		biotransformation
		oxidation
		glucuronidation

QUESTION 21

Type II allergic drug reactions are described as:

		immediate hypersensitivity
		antibody-dependent cytotoxic hypersensitivity
		delayed-type hypersensitivity
		immune complex-mediated hypersensitivity

Answer 1

Q 19)  Loading dose:

It is a large initial dose of a substance or series of such doses given to rapidly achieve a therapeutic concentration in the body. A loading dose is most useful for drugs that are eliminated from the body relatively slowly, i.e. have a long systemic half-life. Such drugs need only a low maintenance dose in order to keep the amount of the drug in the body at the appropriate therapeutic level, but this also means that, without an initial higher dose, it would take a long time for the amount of the drug in the body to reach that level.

Drugs which may be started with an initial loading dose include digoxin, teicoplanin, voriconazole, procainamide and fulvestrant.

Q 20) Biotransformation

Drug metabolism is the term used to describe the biotransformation of pharmaceutical substances in the body so that they can be eliminated more easily. The majority of metabolic processes that involve drugs occur in the liver, as the enzymes that facilitate the reactions are concentrated there. Drug metabolism or biotransformation is vitally important to our understanding of the time course of drugs in the body, the structuring of dosage regimens, the pharmacology and toxicology of drug metabolites, and the interactions of multivalent drug combinations.

Q 21) Antibody- dependent cytotoxic hypersensitivity
Type II reactions involve IgG-mediated cytotoxicity directed to the membranes of erythrocytes, leukocytes, platelets, and probably hematopoietic precursor cells in the bone marrow. Drugs that are typically involved are methyldopa (hemolytic anemia), aminopyrine (leukopenia), and heparin (thrombocytopenia).