Posologie

Posologie, or posology in pharmacology, refers to the study and application of dosing regimens for medications. It covers how much drug to give (dose), how often (frequency), how long (duration), and by which route of administration. The goal is to achieve effective therapeutic exposure while minimizing adverse effects.

Determining posology relies on pharmacokinetics (absorption, distribution, metabolism, elimination) and pharmacodynamics (drug effects, dose-response relationships). Guidelines consider the indication, formulation, and patient characteristics to establish appropriate dosing schedules.

Factors affecting dosing include body weight or surface area, age, renal and hepatic function, pregnancy or lactation, genetic factors influencing metabolism, concomitant diseases, and interactions with other medicines or food. Dosing concepts such as loading doses to rapidly achieve therapeutic levels, maintenance doses to sustain effect, and titration to optimize response are commonly used. Doses are often expressed in mg per kg for children and in fixed amounts for many adults. Adjustments are made for organ impairment and during long-term therapy to avoid accumulation or toxicity.

Special populations require careful consideration. Pediatric posology typically uses weight-based calculations; elderly patients may require lower doses due to reduced clearance and increased sensitivity; pregnancy considerations balance maternal benefit with fetal risk.

Safety and monitoring are integral. Therapeutic drug monitoring is used for drugs with narrow therapeutic windows. Adherence, timing, and accurate dosing are essential, and clinicians adjust regimens based on response and adverse effects.

Posology is guided by clinical guidelines, regulatory approvals, and product labeling, but clinicians tailor regimens to individual needs, sometimes using off-label dosing within evidence-based practice.

Summary: Posology provides a framework for delivering medicines safely and effectively by specifying dose, route, and schedule, and by adapting regimens to patient-specific factors.