Tramadol is an opioid analgesic. It is indicated for the relief of moderate to
moderately sever pain across the full range of acute and chronic pain syndromes. Due
to its short half-life (5 to 7 hours) and its short duration of action (3 to 7 hours), it was
highly desirable to slow the rate of absorption of tramadol and spread the absorption
process over a longer interval, with increasing patient compliance and decreasing the
risk and severity of adverse effects. Consequently, sustained release tramadol tablets
were prepared utilizing the following materials: Compritol (CT), Plantago (PT),
Pectin (PC), and HPMC. The inclusion of HPMC with CT, prolongs the release of
tramadol more than CT alone. Also, by increasing HPMC concentration more
sustaining effect could be obtained, but at 15% less sustaining effect was observed.
The inclusion of NaAlg retards the release more than NaCMC, either with or without
Avicel. PC showed pronounced sustaining effect with NaAlg alone (either with or
without Avicel) compared to those containing NaCMC alone or with NaAlg. However,
in case of tablets containing PT; the inclusion of NaCMC, either alone or in
combination with NaAlg, retards the release of drug more than NaAlg alone. Aiming
for more sustaining properties smaller tablets (250 mg) containing the same
proportions of CT and HPMC but lower % of Avicel, NaCMC or NaAlg were
prepared. Formula containing NaCMC alone showed the most sustaining effect (more
than Tramal®) followed by those including NaCMC and Avicel.