Tramadol hydrochloride is a synthetic
opiate agonist with a plasma elimination half-life of 5 to 6 hours and peak plasma levels at about 1 1/2 hours. It derives its activity from attachment to the
mu-receptor and blockage of
norepinephrine reuptake. The purpose of this single-dose, double-blind, placebo-controlled study was to determine the
analgesic effectiveness of an
oral administration of two dose levels of
tramadol hydrochloride (75 or 150 mg) compared with the combination of 650 mg
acetaminophen plus 100 mg
propoxyphene napsylate in 161 patients with severe
postoperative pain after
cesarean section.
Analgesia was assessed over a 6-hour period. Treatments were compared on the basis of standard scales for
pain intensity and relief and a number of derived variables based on these data. A global rating of the study medication was also used to compare treatments. The three active treatments were effective
analgesics, statistically superior to placebo for many hourly and summary measures. A dose response was seen between the two
tramadol doses, with the 150 mg dose providing significantly greater
analgesia over the lower dose. The 75 mg dose of
tramadol was generally more effective than the
acetaminophen-propoxyphene combination after hour 2, and significantly so for some hourly time points, as well as for the global rating of the medication. The 150 mg dose of
tramadol was significantly more effective than the
acetaminophen-propoxyphene combination from hour 2 through hour 6 for the sum of
pain intensity differences and total
pain relief scores, as well as for the global rating of the medication.
Tramadol hydrochloride at both dose levels is an effective
analgesic agent and at 150 mg is statistically superior to the
acetaminophen-propoxyphene combination. No serious adverse effects were observed; however,
dizziness was more frequently reported with 150 mg
tramadol.