As people age, the efficiency of various regulatory processes that ensure proper communication between cells and organs tends to decline. This deterioration can lead to difficulties in maintaining homeostasis during physiological stress. This includes but is not limited to cognitive impairments, functional difficulties, and issues related to caregivers which contribute significantly to medication errors and non-adherence. These factors can lead to higher morbidity, extended hospital stays, reduced quality of life, and even mortality. The decrease in homeostatic capacity varies among individuals, contributing to the greater variability observed in geriatric populations. Significant pharmacokinetic and pharmacodynamic alterations accompany ageing. Pharmacokinetic changes include decreased renal and hepatic clearance and an increased volume of distribution for lipid-soluble drugs, which prolong their elimination half-life. Pharmacodynamic changes typically involve increased sensitivity to various drug classes, such as anticoagulants, antidiabetic and psychotropic medications. This review examines the primary age-related physiological changes in geriatrics and their impact on the pharmacokinetics and pharmacodynamics of medications.