Tachyphylaxis

Tachyphylaxis

Question 1. Enumerate Factors Modifying Drug Response. Describe Drug Tolerance With Suitable Examples.
Answer:

Enumeration Of Factors Modifying Drug Response

• Body size
• Age
• Sex
• Genetic variation
• Routes of administration
• Environmental factors and time of administration
• Psychological factors
• Pathological state
• Other drugs
• Tolerance.

Drug Tolerance May Be

• Natural: The species or individual are inherently less sensitive to the drug, for example, black races are tolerant to mydriatics.
• Acquired: Acquired tolerance develops due to repeated use of a drug, for example, tolerance develops to the sedative action of chlorpromazine.
  Tolerance develops to the analgesic and euphoric action of morphine.

Question 2. Write A Short Note On Tachyphylaxis.
Answer:

Tachyphylaxis

Tachyphylaxis is also known as acute tolerance. Tachyphylaxis is the rapid development of tolerance after repeated administration of the drug at shorter intervals.

• This is usually seen with indirectly acting drugs, for Example. ephedrine, tyramine, and nicotine.
• These drugs act by releasing catecholamines in the body, i.e. by gradual loss of noradrenaline, and synthesis from adrenergic nerve endings.
  So repeated administration of the drug leads to the gradual depletion of neurotransmitters and there is a reduction in the response.
• Other mechanisms like slow dissociation of the drug from its receptor thereby blocking the receptor, internalization of the receptor, homeostatic adaptation, etc. may also be involved.