ZeroOrderFreisetzung

ZeroOrderFreisetzung, or zero-order release, is a drug release mechanism in which the amount of drug released per unit time remains constant, independent of the remaining amount within the dosage form. In mathematical terms, the release rate dM/dt is constant (k0), leading to a linear increase of the cumulative amount released M(t) over time. This is in contrast to first-order release, where the rate decreases as the available drug is depleted. In practice, zero-order release is an idealization; many systems approximate zero-order behavior for a portion of their life span.

Achieving true zero-order release requires careful design to maintain a constant driving force and surface area for release. Common approaches include osmotic pump systems and reservoir-type devices with semipermeable membranes and constant orifice flow, which can produce near-constant output. Other strategies rely on swellable or erodible polymer matrices that regulate drug diffusion or dissolution at a steady rate, and on ion-exchange resins that provide a consistent trade-off between release sites and available drug. Transdermal patches and some long-acting oral formulations are designed to approximate zero-order release to maintain steady plasma concentrations.

Applications of zero-order release concepts include long-term drug therapies, pain management, and treatments requiring tight concentration control. While true zero-order kinetics are difficult to achieve and maintain in vivo, many products aim for a near-zero-order profile over a defined time window to reduce peaks and troughs and improve therapeutic outcomes. Assessment of release behavior typically involves in vitro dissolution testing and fitting to kinetic models to evaluate linearity and duration of the near-constant release phase.