Propoxyphene, plasma clearance

BETA-BLOCKERS OPIOIDS 1. Risk of t plasma concentrations and effects of labetalol, metoprolol and propranolol t systemic effects of timolol eye drops 2. t plasma concentrations of esmolol when morphine is added 3. t plasma concentrations of metoprolol and propranolol when dextro-propoxyphene is added 1. Methadone inhibits CYP2D6, which metabolizes these beta-blockers 2. Unknown 3. i hepatic clearance of metoprolol and propanolol 1. Monitor BP at least weekly until stable 2. Monitor BP closely 3. Monitor BP at least weekly until stable. Warn patients to report symptoms of hypotension (lightheadedness, dizziness on standing, etc.)... 

In the absence of its antipode, an enantiomer may exhibit greater pharmacological activity. This is possible when a less active enantiomer acts as an antagonist or one accelerates clearance of the other. For example, in the rat, the analgesic effects and plasma concentration of d-propoxy-phene are enhanced in the presence of /-propoxyphene (26). Conversely, as compared to the racemate, plasma concentrations of flurbiprofen enantiomer seem to increase when either enantiomer is given alone to both humans and rats (27,28). An opposite observation has been reported for indobufen in the rat and mouse (29),... 

After oral administration, concentrations of propoxyphene peak at 1-2 hours. There is great variability between subjects in the rate of clearance average t ofpropoxyphene in plasma after a single dose is 6-12 hours, which is longer than that of codeine. In humans, the major route of metabolism is H-demethylation to yield norpropoxyphene, which has a t of 30 hours and may accumulate to toxic levels with repeated doses. 

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