Question

What are the similarities and differences between allergic responses and personal responses to drugs?

Answer 1

Similarities between allergic responses and personal responses to drugs:

• Allergic response to a drug is a type of hypersensitivity reaction to the drug.
• Personal response is the inter-individual variation in the response to a drug.
• Allergic response could be a personal response.
  • Not all individuals will develop allergic reaction to a particular drug.
  • Allergic reaction to a particular drug is depends upon genetics of the patient, history of atopy (allergic tendency), upbringing ( children who play in mud tend to have less number of allergies in adulthood)
  • The severity of allergic reaction also varies from individual to individual.
  • Some patient develop mild wheal and flare skin reaction and some may develop life-threathening laryngeal edema.

Disimilarities between allergic responses and personal responses to drugs:

• Personal response is the inter-individual variation in the response to a drug.
• A particular drug has dissimilar effects in different people.
• The factors that influence personal response are:
  • Variability in gastrointestinal drug absorption of a drug.
  • Hepatic enzyme metabolism -
    • Example: Some patients are fast and slow acetylator of isoniazid (anti-TB drug)
    • Fast acetylators tend to metabolize the drug and convert it into an inactive metabolite. This metabolite has no pharmacological action
    • Slow acetylators tend to metabolize the drug slowly. As a result, a high concentration of the drug remains in the patient's blood. This can lead to toxicity.
  • End receptor resistance - The target receptor are not responsive to the drug.
• Therefore, a particular drug can give rise to a higher pharmacological response in one patient and no or lesser pharmacological response in another individual.
• Allergic reaction are mediated by
  • IgE antibodies directed against the drug. There immunoglobulin can cause degranulation of the mast cells and lead to release of chemicals. these chemical can cause increase in blood flow and recruitement of inflammatory cells.
  • Antigen and antibody complex deposition in various tissues of the body.
  • T cell mediated hypersensitivity reaction ( type IV hypersensitivity reaction)