Determination of consistency in pH of some commercial herbal formulations in Ghana

Introduction

There are no strict pH standards for herbal formulations; however, pH can affect the characteristics of drugs and herbal formulations. In this study, the pHs of different herbal formulations produced in the past two batch years at the Centre for Plant Medicine Research (Mampong-Akuapem, Ghana) were analysed. We aimed to evaluate pH consistency among the formulations and suggest suitable pH ranges for the different product classes.

Methods

The formulations analysed were 17 decoctions, three ointments, and nine powders. Suitable ointment and powder samples were prepared before pH was measured, whereas decoctions were analysed directly.

Results

We found that 93.1% of the preparations had average pH < 7 over the two years. The pH values for the decoctions, ointments, and powders were 3.507−6.755, 5.153−5.700, and 5.413−10.719, respectively. Differences in pH over the two production years were not statistically significant for all the powder and ointment formulations as well as for majority of the decoctions (82.4%). This indicates pH consistency for approximately 90% of the products, possibly pointing to consistencies in plant material compositions, formulation conditions, and process parameters.

Conclusions

From our data and reported literature, we recommend that the labels of oral herbal preparations with pH < 5.5 should include an instruction to dilute the product before intake, or to drink water or rinse the mouth after intake to prevent enamel erosion. Decoctions may also be taken after food. Additionally, pH ranges of 4.6−7.0 and 4.0−6.0 may be suitable for rectal and topical herbal formulations, respectively.