Physical and Release Properties of Metronidazole Suppositories TA Adegboye and OA Itiola

Abstract

In order to better understand how to optimize the rectal formulation of metronidazole, this research examined the
physical and release features of metronidazole suppositories and how various bases and adjuvants affected these
qualities.
The following steps were used to make suppositories: (1) witepsol (H15 and E75) and (2) polyethylene glycol (PEG
2850 and 4650) bases containing 200 mg of metronidazole each; as adjuvants, various amounts of Tween 80,
sodium salicylate, and methylcellulose were used. In addition to the crushing strength, disintegration time, and time
for 80% metronidazole release (t80), the suppositories' setting time, solidification point, and melting range were
also determined.
The results showed that witepsol H15 had the shortest setting time of the suppositories, followed by PEG 2850,
witepsol E75, and PEG 4650. In contrast, the order of solidification point, melting range, crushing strength,
disintegration time, and the time it took for 80% of metronidazole to be released from the suppositories (t80) was
the exact opposite of the ranking for setting time. For the suppository formulations, the ideal amounts of Tween 80
and sodium salicylate were noted. The Kitazawa plots revealed that at time t1, all of the formulations had two
dissolving rate constants, k1 and k2, which intersected. Formulations with 5 to 20% w/w methylcellulose displayed
a third dissolution rate constant, k3, which intersected with k2 at time t2.
In conclusion, the bases and adjuvants used have a significant impact on the physical and release characteristics of
metronidazole suppositories. While methylcellulose is effective for sustained-release metronidazole suppositories,
tween 80 and sodium salicylate are likely only suitable for use in formulating immediate-release suppositories.
Parameters determined from Kitazawa plots may provide some light on these findings.