Question

Patient CB has a history of strokes. The patient has been diagnosed with type 2 diabetes, hypertension, and hyperlipidemia. Drugs currently prescribed include the following: Glipizide 10 mg po daily HCTZ 25 mg daily Atenolol 25 mg po daily Hydralazine 25 mg qid Simvastatin 80 mg daily Verapamil 180 mg CD daily

Describe how changes in the pharmacokinetic and pharmacodynamic processes might impact the patient’s recommended drug therapy.

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Answer 1

Pharmacokinetic

Age

pharmacokinetics of different medications are influenced by age and it can also lead to

drug toxicity. With aging there is more chance for adverse drug reactions and drug interaction. It can reduce the metabolism of drugs and also reduction in hepatic clearance. In elderly patients decreased renal function leads to decrease in blood flow, decreased GFR rate , decreased tubular secretion and also cause increase in filtration . As the renal function is reduced it will leads to decrease in drug metabolism and leading to toxicity and adverse drug reactions.

Decrease in body water content - it is another physiologogical change associated with age . Increased body fat and decreased BMI can affect the metabolism and distribution of drugs . Water soluble drugs and lipophilic drugs also affect the distribution of drugs .In case of water soluble drugs they have smaller distribution and have increased concentration.But in case of lipophilic drugs they have increased distribution .This can lead to toxicity .

Pharmacodynamics

The elderly patients are more prone to drug interaction due to age related changes like

Change in homeostatic mechanisms which autonomic reflexes, temperature, thirst.

physiological changes which affects the pharmacodynamics are ventricular arterial stiffness,humoral factors,endothelial function,electrical conduction,cognition.

There is also a chance of developing allergies due to decreased production of clotting factors.With aging individual are more sensitive to a antihypertensive medications due to the weak response produced by baroreceptor and sympathetic neural systems.