Factors affecting drug action in Pharmacology

Before prescribing any pharmaceutical medicine, the physician should consider certain factors that can modify the effect of the drug. The same dose of a drug can produce different degrees of response in different patients and even in the same patient under different situations. The Important factors modify the effect of a drug are subdivided into two groups: patient related factors and drug related factors.
• Patient related factors: age, gender, body weight, presence of food, drug allergy, genetic variation, environmental state, pathological state, psychological state, etc.
• Drug related factors: physical state of a drug, route of drug administration, time of drug administration, drug cumulation, drug combination, drug tolerance, drug dependence, etc.

1. Factors affecting drug action Prof. Amol B. Deore Department of Pharmacology MVP’s Institute of Pharmaceutical Sciences, Nashik

2. Introduction Before prescribing any pharmaceutical medicine, the physician should consider certain factors which can modify the effect of the drug. The same dose of a drug can produce different degrees of response in different patients and even in the same patient under different situations.

3. Patient related factors

4. Drug related factors

5. Patient Related Factors

6. Age

7. Geriatric age

8. Gender Drug response in male and female are not similar. Physiological differences such as Body fat, Body-mass index, Surface area, Total body water, CYP isoenzymes Hormonal influences

9. Body weight Average dose of drug: milligram as a single dose adult weighing between 50 and 100 kg. The dose of the drug should be adjusted for -abnormally slim (underweight persons) -obese persons (overweight persons) -edema, dehydration, malnutrition or skinniness.

10. Dose calculation Dose to be prescribed= Weight in kg x Adult dose 70 Dose to be prescribed= Body surface area in m 2 x Adult dose 1.7

11. Presence of food in stomach

12. For example

13. Drug allergy The drug allergy is abnormal hypersensitive response to a medication One person may develop an allergic reactions when taking a certain medication, while another person on the same drug may have no adverse reaction at all.

14. Genetic variation

15. Genetic variations in drug response are :

16. Environmental state

17. Pathological state The presence of any pathological abnormality in the body shows variation in drug response.

18. Psychological state

19. Placebos

20. DRUG RELATED FACTORS

21. Physical state of a drug

22. Route of drug administration

23. For example

24. Time of drug administration

25. Drug cumulation

26. Drug combination

27. Additive effect (Summation )

28. Synergism

29. Antagonism

30. Drug tolerance

31. Natural tolerance

32. Species tolerance

33. Racial tolerance

34. Acquired tolerance

35. Tissue tolerance

36. Cross tolerance:

37. Pseudotolerance

38. For example- the ancient kings were much worried about the poison threat. So they consumed small doses of arsenic poison orally from their childhood to develop resistance to poison threat.

39. Acute tolerance

40. Drug dependence

41. For example- morphine , codeine, methadone, ethyl alcohol, barbiturates, paraldehyde, chloral hydrate, meprobamate , benzodiazepines, methaqualone, amphetamine, methamphetamine etc.

42. Question Bank

43. Thanking you