Analgesia, plasma levels, and dosage of propoxyphene.

It can be shown that both the mean plasma levels observed and the mean analgesic scores (effectiveness) are related to the dose of an orally effective analgesic agent, although wide individual variations exist. Based on the pharmacokinetic characteristics of propoxyphene, it can be predicted and confirmed that equilibrium (or steady state) plasma levels will be achieved after about six doses when administered on a q. 6h. schedule. Similar predictions indicate that an initial loading dose of 2 to 2 1/2 times the maintenance dose will produce more promptly plasma levels within or close to the equilibrium levels.