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Anti-inflammatory activity and accelerated stability studies of crude extract syrup of <i>Cannabis sativa</i>

Wilfred O. Obonga
Charles O. Nnadi
Sunday N. Okafor
Edwin O. Omeje
Patrick Igbinnaduwa
Charles O. Okoli
Patience O. Osadebe


Purpose: To formulate Cannabis sativa-based syrup and investigate its anti-inflammatory potential and the stability of the formulation under stress conditions.

Methods: The syrup was prepared using different combinations of crude C. sativa resin, propylene glycol, aspartame, sucrose, sodium metabisulphite (SMBs) and ethylenediaminetetraacetic acid (EDTA). The stability of the formulations was determined under accelerated temperature conditions. The anti-inflammatory activity of the resin and different formulations were evaluated by the egg albumin induced paw edema model in rats. Biochemical assay was determined by Reitman and Frankel colorimetric assay method while hematological assay was evaluated by standard protocols.

Results: EDTA-containing syrup (CE) was the most stable with estimated shelf-life of 2204 days (K25ºC, 4.78 x 10-5/day). Higher propylene glycol levels significantly improved anti-inflammatory activity compared to those containing a lower amount. All the formulations showed anti-inflammatory activity higher than the crude resin with a dose-dependent inhibition of paw edema compared with the control. There was no significant difference (p < 0.05) between the serum glutamate-oxaloacetate transaminase (SGOT, 13.821 ± 0.190 - 16.008 ± 1.012), serum glutamate-pyruvate transaminase (SGPT, 19.241 ± 1.027 - 22.901 ± 1.093) and urea (9.812 ± 0.252 - 10.054 ± 0.252) levels of the treated and 16.856 ± 1.053, 24.960 ± 0.101 and 10.654 ± 0.925 units/L of the control animals respectively. With the exception of eosinophil that disappeared from the blood in the third week, all the hematological parameters showed a gradual increase in lymphocytes, neutrophils, monocytes, packed cell volume (PCV), white and red blood cell counts in the third week compared to control.

Conclusion: Formulation of C. sativa as syrup using efficient carriers improves the pharmacological activity of the crude extract. SMBs and EDTA significantly enhance the stability of the syrup with no observable biochemical and hematological changes in treated animals

Keywords: Cannabis sativa, Syrup, Anti-inflammatory, Stability, Hematological