Tmax

Tmax is the time post-administration at which Cmax is reached. For SC-injected peptides, Tmax is typically 1–4 hours; for IV administration, Tmax is essentially immediate; for oral compounds with intestinal absorption (MK-677, orforglipron) Tmax is 2–4 hours.

Tmax is operationally important because it tells the researcher when to time a dose around training, sleep, or another stack member. Ipamorelin’s short Tmax (~30–60 min) is why it is dosed pre-bed: the GH pulse lands during early slow-wave sleep when endogenous GH release peaks anyway, producing additive rather than competing signaling.

Long-Tmax modifications (DAC tagging, acylation) trade peak height for sustained coverage — useful for compounds where steady receptor occupancy matters more than pulsatile exposure.