Age-related factor on pharmacodynamics and pharmacokinetics of drugs.
Pharmacodynamics is described as the study of what the drug does to the body, while pharmacokinetics studies what the body does to the drug. Pharmacodynamics is concerned with the biochemical, molecular, and physiologic drug effects due to receptor binding and chemical interactions. On the other hand, pharmacokinetics is concerned with the absorption, distribution, metabolism, and clearance of the drug. Different factors affect the pharmacodynamics and pharmacokinetics of drugs. Age is one of the important and common factors that should be considered during prescription medications (Rosenbaum, 2016)
How age affects the pharmacodynamics and pharmacokinetics of drugs.
Aging is a common factor that influences the pharmacologic and pharmacokinetic properties of drugs. Aging is responsible for reducing the homeostatic capacity of the body by altering the structural and functional characteristics of organ systems. An increased volume of distribution of drugs and reduced elimination in the elderly is due to the changes in body composition, hepatic functions, and renal functions. These are the factors that are responsible for the changes in the pharmacokinetic profiles of drugs. A reduced metabolism rate and the elimination of the drug in the body are responsible for the increased half-life of the drug and increased risks of adverse drug reactions and toxicity (Murphy, 2005). Pharmacotherapy for Cardiovascular Disorders NURS-6521 week 2 Assignment.
How changes in the processes impact the patient’s recommended therapy.
According to a comparative study by (K M Sowinski, 1995) on the effects of aging on the pharmacokinetics and pharmacodynamics of atenolol, data obtained suggested the changes observed in the pharmacokinetics of atenolol with age were due to the reduced renal clearance in the elderly, making them more sensitive to the medication. Similar medications that are extensively excreted renally, such as hydralazine, verapamil, glipizide, and hydrochlorothiazide, are prone to a similar fate in cases of reduced renal function due to age. Aging also affects the pharmacodynamics properties of medications through the relative increase of sensitivity to drugs common in the elderly. This is often attributed to the impairment of the body’s homeostatic compensatory mechanisms and altered response to receptor stimulation in old age. Pharmacotherapy for Cardiovascular Disorders NURS-6521 week 2 Assignment. A better understanding of age-related pharmacodynamics and pharmacokinetics changes is imperative for the rational, evidence-based prescription of medications, especially cardiovascular medications, to ensure optimum safety and efficacy (Murphy, 2005).
The absorption, distribution, metabolism, and excretion of medications are generally affected by age as a factor, hence the pharmacokinetic profile. The general body fat increases with age, while the total body water decreases. This causes an increased volume of distribution of lipophilic drugs as well as their clearance half-life. The decreased serum albumin concentration in the body during old age are additional factors that pose a challenge in the prescription of medications in the elderly (Gabrielle Koutoukidis, 2020).
The age-related risk of rhabdomyolysis using statins such as simvastatin is an area of concern in the management of hypercholesterolemia and the prevention of cardiac events. This is more common in the elderly with concomitant medications and comorbidities that increase the risk of myopathy and decrease its metabolism and elimination, such as decreased hepatic and renal functions in the elderly. Pharmacotherapy for Cardiovascular Disorders NURS-6521 week 2 Assignment. The decreased muscle mass and body weight at old age are additional risk factors that predispose the elderly to such adverse effects. Prescription of the statins in the elderly is hence dependent on the risk-benefit ratio of the medication (Richard A. Helms, 2006).
Recommendations to improve the patient’s therapy outcome.
Dosage modification of such medications with regular monitoring of the plasma therapeutic levels is advised in elderly patients with significantly reduced renal function. Discontinuation of the medication is advised in events whereby the risk of adverse effects outweighs the benefit. Discontinuation is also indicated when the elderly individual needs medication with potential interaction with the statin causing potential adverse effects. Concurrent administration of verapamil with simvastatin increases the level and effects of simvastatin by affecting CYP3A4 metabolism, increasing the risk of myopathy. Alternative medication to simvastatin is recommended to improve this patient&rsqu
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