Dose Of A Drug

Dose Of A Drug

Define A Dose Of A Drug. Describe Any Six Factors Modifying The Action Of A Drug.
Answer:

Dose Of A Drug

• The dose of a drug is the quantity needed to be administered to produce adequate concentration in blood so that desired response can be obtained in a given patient.
• It is qualified and quantified in terms of response to be achieved and expressed as a range. Example. analgesic dose of aspirin is 0.3 to 0.6 gm while its dose for producing anti-inflammatory effect in rheumatoid arthritis is 3 to 6 gm.

Factors Modifying Drug Action

Variation in the response to the same dose of the drug, in different patients, and even in the same patient on different occasions is a rule rather than expansion.

The various factors that can be modifying drug effect are:

• Body size: The larger the size more can be the dose required to produce the same effect.
• Age: Infants, children, and elders are more sensitive to drug effects because it depends on the process of metabolism and excretion of the drug and they do have not well-developed systems.
  While in later they deteriorate with the advancing age.
• Sex: Females have smaller body sizes and require doses of the lower side of the range.
  • Androgens are unacceptable to women and estrogen to men.
  • Gynecomastia is a side effect that occurs only in men not in women.
• Genetic variation: It leads to a change in the rate of drug metabolization which increases or decreases the quantity of metabolizing enzyme.
• Routes of administration: They govern the speed and intensity of drug response, for example, magnesium sulfate given orally acts as a laxative.
  Applied locally act as an anti-inflammatory and when given IV it produces CNS depression.
• Environmental factors and time of administration: Several environmental factors affect the drug response. Exposure to insecticides, carcinogens, and tobacco smoke induces drug metabolism.
  Hypnotics taken at night and in quiet, familiar surroundings may work more easily.