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ABSTRACT
Hypertension management is one classical example where co-administration of various drugs and food types is used as therapy. These combinations are of immense benefit to patients but there are also likelihoods of drug-drug and drug-food interactions. Besides the conventional drugs used in hypertension management, various herbal preparations like Hibiscus sabdariffa (HS) extract (Zobo), have been shown to have antihypertensive effects and this herbal preparation is used in both developing and developed countries. Sometimes, this Hibiscus sabdariffa extract (Zobo) is taken concomitantly with an anti-hypertensive drug with no regard for potential herb-drug interaction. Different brands of A/H tablets were purchased and tested for their tablet properties. Commercially prepared Zobo was purchased from local market, and a plain sample was prepared in the laboratory. Interaction between HS and the drug was assessed with the disintegration time, dissolution profiles of the tablets and Fourier Transform Infra-Red Spectroscopy (FTIR) in the presence and absence of HS. Drug content was analysed using High-Performance Liquid Chromatography (HPLC). Preliminary results showed that all the brands of A/H met official specifications in terms of physiochemical properties with tablet weights ranging from 0.19 ± 0.01- 0.26 ± 0.02 g, 4.65 ± 0.01-8.30 ± 0.01 kp for tablet hardness, 0.2 ± 0.1-0.4 ± 0.1% for tablet friability and 0.7 ± 0.2-3.1 ± 0.7 min for tablet disintegration times. The FTIR spectrum of pure hydrochlorothiazide and amiloride showed similar pattern with that of Zobo/hydrochlorothiazide and Zobo/amiloride, respectively. There is no significant in-vitro interference with the disintegration of A/H tablets in the presence or absence of the different types of Hibiscus sabdariffa aqueous extract (Zobo). In the HPLC spectra of Zobo + amiloride and Zobo + hydrochlorothiazide, it was observed that both compounds were eluting at the same time and their retention time was also the same. The rate of drug release was significantly higher in 0.1 N HCl compared to the one in the presence of Zobo (p < 0.05). Generally, the amount of drug dissolved from the tablets increased with time. For example, 98% of A/H was released from Zoretic in 1 hour in the presence of Zobo. The different brands of Amiloride/Hydrochlorothiazide met the Pharmacopeia requirements where they all passed the disintegration, dissolution, and weight uniformity requirements of the official compendium. Hibiscus sabdariffa leaves extract (Zobo) has been shown not to possess significant in-vitro interaction with the active ingredients in amiloride/hydrochlorothiazide tablets and as such, there should not be much concern about concomitant oral administration except if further in-vivo investigation, proves otherwise.
