1. Chapter 9 PHARMACOKINETICS VARIABILITYby
Dr. Arshad Ali Khan Faculty of Engineering Technology

2. PHARMACOKINETICS VARIABILITY
Definition : Due to differences in drug concentration at the site of action because of inter-individual differences in drug absorption, distribution, metabolism and excretion.
Also known as inter-individual variations of a drugs pharmacokinetic parameters, resulting in different pharmacokinetic profiles after administration of the same dose to different patients.

3. FACTORS AFFECTING THE PHARMACOKINETIC VARIABILITY IN DISEASES STATES

4. Body weight
Same drug dose administration with different body weight individuals may results into different plasma profile
The dose adjustment according to the body weigh individual (obese and thin) can reduce the pharmacokinetic variability.
In the obese patients, it is difficult to reduce the pharmacokinetic variability of drug because the recommended dose of the drugs are normally based on the body weight of the normal individuals. This pharmacokinetic variability is due to the function of organs such as kidney and liver is different from the normal individuals.

5. Elderly subjects (more than 70 years)
Age
Age can affect the distribution and elimination of drugs
Drug protein binding, drug metabolism and drug excretion may change according to age
There are 5 groups :
Infants (1-12 months)
Newborns (-3 days)
AGE
Children (4-9 years)
Adults (16-37years)
Elderly subjects (more than 70 years)

6. Sex
The body size are different for both men and women which led to different volume of distribution and different drug clearance.
Higher body fat in female may enhance the volume of distribution for the lipophilic therapeutic agents.
The oral bioavailability in somewhat higher in female in comparison to male.
Bioavailability after transdermal drug administration does not appear to be significantly affected by gender; nor does protein binding.
The transdermal drug administration are not affected by sex.

7. References References
Wyatt, C. M., Kim, M. C., & Winston, J. A. (2006). Therapy Insight: How Changes in Renal Function With Increasing Age Affect Cardiovascular Drug Prescribing. Retrieved from Nat Clin Pract Cardiovasc Med:
S.M. Hanning, J. M.-G. (2015, february 1). Investigation into the dosage form attributes of currently UK licensed cardiovascular and parkinson's disease drug products. Retrieved from science direct:
Pharmacokinetic variability. (2011, march 29). Retrieved from slide share:
Pharmacokinetic variability. (N.D.). Retrieved from
Mick, R. (N.D.). Drug interactions. Retrieved from
Philip R orlander, M. (2016, 12 july). Hypothyroidism treatment & management. Retrieved from emedicine.Medscape.Com:
References

8. Ötles, S. (2014). Food and drug interactions. Acta sci. Pol. , Technol
Ötles, S. (2014). Food and drug interactions. Acta sci. Pol., Technol. Aliment. Retrieved from
Schwartz, J. B. (2003). The influence of sex on pharmacokinetics. Clinical pharmacokinetics, 42(2),
Mangoni, A. A., & Jackson, S. H. (2004). Age‐related changes in pharmacokinetics and pharmacodynamics: basic principles and practical applications. British journal of clinical pharmacology, 57(1),
De Baerdemaeker, L. E., Mortier, E. P., & Struys, M. M. (2004). Pharmacokinetics in obese patients. Continuing Education in Anaesthesia, Critical Care & Pain, 4(5),
Belle, D. J., & Singh, H. (2008). Genetic factors in drug metabolism. American family physician, 77(11).

9. Thank you