Potency Evaluation of Expired Morphine Sulphate Injections
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Date
2021-03-31
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Faculty of Pharmaceutical Sciences, Ahmadu Bello University
Abstract
Expired drugs have not necessarily lost their potency and efficacy as expiration dates are only assurances that the labeled potency will last at least until that time. Clinical situations may arise in which expired medicines might be considered owing to lack of viable alternatives or financial concerns. Moreover, limited studies have reported potency of pharmaceuticals beyond their labeled expiration dates. This study determined the potencies of expired morphine sulphate (10 mg and 15 mg) injections using British Pharmaceutical Codex specific absorptivity [E (1%, 1 cm)] values of 41 [at wavelength of maximum absorbance (λmax) of 285 nm] in water and 70 [at λmax of 298 nm] in 0.1N NaOH and compared with that of unexpired morphine hydrochloride (10 mg) injection. With the exception of expired morphine 15 mg injection, both the unexpired and expired 10 mg injections exceeded the United State Pharmaceutical Codex maximum acceptance limit of 110.0% (acceptance criteria of 90.0%-110.0%). Although the percent contents of expired morphine 15 mg injections were significantly different from those of unexpired morphine 10 mg injections [mean percent content difference (95% confidence interval): 13.98% (11.05, 16.92) using water and 13.02% (8.95, 17.08) using 0.1N NaOH], expired morphine 10 mg injections were not significantly different from the unexpired morphine 10 mg injections [2.68% (-0.56, 5.92) using water and 7.33% (-3.40, 18.06) using 0.1N NaOH as assay solvents]. This study corroborates a previous report and indicates that expired morphine injections, if properly stored, can be extended past their expiration dates. While it is always best to use unexpired medication, expired morphine injections could be considered when it becomes the sole available option.
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Keywords
Expiration dates; Expired medicines; assay; morphine injection; potency evaluation