Piekfase

Piekfase, in Dutch, is a term used primarily in pharmacology and pharmacokinetics to describe the period during which the concentration of a substance in the blood plasma reaches its maximum after administration. After reaching this peak, the concentration typically declines as the drug is distributed and eliminated from the body.

Key concepts are Tmax, the time to reach the maximum plasma concentration (Cmax). The height of the peak is Cmax. The timing and size of the peak are influenced by the rate of absorption and the rate of elimination; rapid absorption tends to produce a higher and earlier peak, while slower release or absorption tends to lower and delay the peak.

Determining the piekfase has practical implications for therapy. It helps forecast the onset of action, plan dosing intervals, and assess the risk of peak-related adverse effects. Formulations designed to flatten peaks, such as sustained-release products, aim to maintain more constant drug exposure and improve tolerability. Factors such as route of administration, food intake, gastric emptying, patient age, organ function, and interactions with other medications can alter the timing and magnitude of the peak.

Limitations: a peak in plasma concentration does not always correspond to the peak pharmacologic effect, which depends on the drug’s pharmacodynamics and receptor interactions. Individual variability can lead to different peak times and magnitudes among patients.

See also: pharmacokinetics, Tmax, Cmax, half-life, sustained-release.