[Opioid effects - galenics make the difference].

The galenics of extended-release opioids is highly variable and often insufficently. The quality of retard formulations can roughly be evaluated by means of 3 parameters: 1. PTF-Value (peak-trough fluctuation) [PTF (%) = [Cmax - Cmin] ×100/Cav] which should be as small as possible in order to minimize the fluctuation of plasma levels e.g. Morphin ratiopharm®: 120 ± 35%; Oxygesic® 120 ± 38%; Jurnista® 61 ± 41%. 2. A maximized Tmax-value (viz. the time required to achieve Cmax) to induce a more gradual onset of opioid effects e.g. MST Continus®: 2,3 ± 1,1h; Palladon® retard: 4,8 ± 0,8h; Hydromorphon STADA®: 5,1 ± 1,4h and Jurnista®: 12-16h. 3. Half-Value-Duration (HVD) is defined as the total time period in which the plasma concentration of opioids is above one-half of Cmax. Therefore, HVD is a parameter for the extent of controlled release. A too short HVD can induce end-of-dose-failure. HVD of most opioid formulations (b.i.d.) is only 6h, better are Morphin-KREWEL® with a HVD of 8,4h and especially Jurnista® (q.d.) with HVD =21,8h. These different galenics ban a so-called "Aut-idem-Substitution" of extended-release opioids. © Georg Thieme Verlag Stuttgart · New York.