Pharmaceutical quality of herbal medicinal products and dietary supplements – a case study with oral solid formulations containing Lavandula species

The effectiveness and safety of regulated herbal medicinal products and dietary/food supplements are key areas of research. However, limited evidence exists of their pharmaceutical performance quality (including the standard in the respective pharmacopeial monographs). We evaluated the applicability of the European Pharmacopoeia general chapter protocols for disintegration testing of oral dosage forms using 73 products containing Lavandula species. Several Lavandula species, hybrids and cultivars are important medicinal plants globally in the phytopharmaceuticals and dietary/food supplement industry, including Lavandula Mill., traditionally used to treat conditions linked to nervousness and sleep disorders. We evaluate the pharmaceutical performance quality, particularly the in vitro disintegration and the phytochemical quality of 73 Lavandula oral dosage forms of single and multi-ingredients with different regulatory statuses. The phytochemical quality testing showed that 63 % of products contain less or none of the main marker compounds (e.g., linalool, linalyl acetate, and cineole). There was also considerable variability of the main marker compounds between products, with some containing 'often/sometimes undeclared' and significant amounts of rapeseed and sunflower oils as excipients. The pharmaceutical performance quality testing showed that 30 % of oral solid formulations always failed the disintegration testing (seven soft gels, ten hard shells, and five tablets/caplets). Pass rates for gelatine-based capsules were higher than for non-gelatine (cellulose-based) capsules. Overall, our findings highlighted problems with the pharmaceutical performance and phytochemical quality of the investigated products. These results have implications for the interpretations of the benefits and risks of phytopharmaceuticals used as compared to dietary/food supplements.