PURPOSE: This scoping review aims to describe the effect of lipid-based formulations on the oral bioavailability of herbal compounds.
METHODS: A systematic search was conducted across three electronic databases (Medline, Embase and Cochrane Library) between January 2010 and January 2021 to identify relevant studies. The articles were rigorously screened for eligibility. Data from eligible studies were then extracted and collated for synthesis and descriptive analysis using Covidence.
RESULTS: A total of 109 studies were included in the present review: 105 animal studies and four clinical trials. Among the formulations investigated, 50% were emulsions, 34% lipid particulate systems, 12% vesicular systems, and 4% were other types of lipid-based formulations. Within the emulsion system classification, self-emulsifying drug delivery systems were observed to produce the best improvements in oral bioavailability, followed by mixed micellar formulations. The introduction of composite lipid-based formulations and the use of uncommon surfactants such as sodium oleate in emulsion preparation was shown to consistently enhance the bioavailability of herbal compounds with poor oral absorption. Interestingly, the lipid-based formulations of magnesium lithospermate B and Pulsatilla chinensis produced an absolute bioavailability greater than 100% indicating the possibility of prolonged systemic circulation. With respect to chemical conjugation, D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) was the most frequently used and significantly improved the bioavailability of its phytoconstituents.
CONCLUSION: Our findings suggest that there is no distinct lipid-based formulation superior to the other. Bioavailability improvements were largely dependent on the nature of the phytoconstituents. This scoping review, however, provided a detailed summary of the most up-to-date evidence on phytoconstituents formulated into lipid preparations and their oral bioavailability. We conclude that a systematic review and meta-analysis between bioavailability improvements of individual phytoconstituents (such as kaempferol, morin and myricetin) in various lipid-based formulations will provide a more detailed association. Such a review will be highly beneficial for both researchers and herbal manufacturers.
METHODS: Drug formulations were administered to the experimental animals via oral, intravenous and intraperitoneal routes. Blood samples were collected at different pre-determined time intervals to determine the pharmacokinetic parameters. To understand the biodistribution profile of HCZ, tissue samples were isolated from different groups of Sprague-Dawley rats at different time points. The pharmacokinetic parameters of HZC were evaluated after administration through oral (100 mg/kg), intraperitoneal (100 mg/kg) and intravenous (10 mg/kg) routes.
RESULTS: Significantly (p oral administration at a similar dose. In addition, shorter time to peak was observed with intraperitoneal administration. These results revealed a faster rate and longer duration of absorption with intraperitoneal administration, which further resulted in enhanced absolute bioavailability of HZC (29.17%) when compared to 5.1% upon oral dosing. The obtained data from the pharmacokinetic study indicated that HZC was instantaneously distributed and moderately eliminated from body fluids.
CONCLUSION: Based on the findings, it could be concluded that absorption of HZC is much higher via intraperitoneal route of administration compared to the oral administration.
OBJECTIVES: GST inhibition activity and characterization of Kanji and methanol extract of D. carota roots, and oral absorption pattern of ferulic acid from Kanji in rats.
MATERIALS AND METHODS: GST inhibition activity of Kanji and methanol extract of D. carota roots in concentration range 0.001-100.00 mg/mL was determined using Sprague Dawley rat liver cytosolic fraction. Methanol extract upon column chromatography gave ferulic acid, which was used to characterize Kanji and determine its oral absorption pattern in Wistar rats.
RESULTS: The GST inhibition activity of Kanji (100.00 μg/mL), methanol extract of D. carota roots (100.00 μg/mL) and tannic acid (10.00 μg/mL, positive control) was found to be 0.162 ± 0.016, 0.106 ± 0.013 and 0.073 ± 0.004 μM/min/mg, respectively. Different Kanji samples and methanol extract contained ferulic acid (0.222-0.316 mg/g) and 0.77 mg/g, respectively. Ferulic acid did not appear in plasma after oral administration of Kanji.
DISCUSSION: Kanji having solid contents 80.0 μg/mL, equivalent to 0.0025 μg/mL ferulic acid, does not inhibit the activity of GST. The oral administration of Kanji, in human equivalent dose (528 mg/kg, 16.67 μg ferulic acid), to rats indicated poor absorption of ferulic acid.
CONCLUSION: Kanji having solid contents 14-36 mg/mL does not inhibit GST activity, hence may not interfere with drugs that are the substrates of GST, if taken concomitantly.
Objective: The current study was conducted to evaluate acute oral toxicity of LA on normal rats.
Methods: The study was conducted in accordance with the Organization for Economic Co-operation and Development guidelines (OECD 423) with slight modifications. LA was administered orally to female Sprague Dawley (SD) rats (n = 6/group) at a single dose of 300 and 2,000 mg/kg body weight, respectively, while normal control received vehicle only. Animals from all the three groups were monitored for any behavioural and toxicological changes and mortality for two weeks. Food and fluid consumption, body weight was monitored on daily basis. At the end (on day 15th) of the experimental period, blood was collected for haematological and biochemical analysis. Further, all the animals were euthanized, and internal organs were harvested for histopathological investigation using four different stainings; haematoxylin and eosin, Masson trichrome, Periodic Acid Schiff and Picro Sirius Red for gross pathology through microscopical observation.
Results: The study results showed no LA treatment-related mortality and morbidity at two different dosages. Daily food and water consumption, body weight, relative organ weight, haematological, and biochemical analysis were observed to be normal with no severe alterations to the internal tissues.
Conclusion: The current finding suggests that single oral administration of LA, even up to 2,000 mg/kg body weight, did not exhibit any signs of toxicity in SD rats; thus, it was safe to be used on disease models in animals.