Sophia Yui Kau Fong

Establishing the Pharmaceutical Quality of Chinese Herbal Medicine: A Provisional BCS Classification

The Biopharmaceutical Classification System (BCS), which is a scientific approach to categorize active drug ingredient based on its solubility and intestinal permeability into one of the four classes, has been used to set the pharmaceutical quality standards for drug products in western society. However, it has received little attention in the area of Chinese herbal medicine (CHM). This is likely, in part, due to the presence of multiple active components as well as lack of standardization of CHM. In this report, we apply BCS classification to CHMs provisionally as a basis for establishing improved in vitro quality standards. Based on a top-200 drugs selling list in China, a total of 31 CHM products comprising 50 official active marker compounds (AMCs) were provisionally classified according to BCS. Information on AMC content and doses of these CHM products were retrieved from the Chinese Pharmacopoeia. BCS parameters including solubility and permeability of the AMCs were predicted in silico (ACD/Laboratories). A BCS classification of CHMs according to biopharmaceutical properties of their AMCs is demonstrated to be feasible in the current study and can be used to provide a minimum set of quality standards. Our provisional results showed that 44% of the included AMCs were classified as Class III (high solubility, low permeability), followed by Class II (26%), Class I (18%), and Class IV (12%). A similar trend was observed when CHMs were classified in accordance with the BCS class of AMCs. Most (45%) of the included CHMs were classified as Class III, followed by Class II (16%), Class I (10%), and Class IV (6%); whereas 23% of the CHMs were of mixed class due to the presence of multiple individual AMCs with different BCS classifications. Moreover, about 60% of the AMCs were classified as high-solubility compounds (Class I and Class III), suggesting an important role for an in vitro dissolution test in setting quality control standards ensuring consistent biopharmaceutical quality for the commercially available CHM products. That is, provisionally, more than half of the AMCs of the top-selling CHMs included in this study would be candidates for a bioequivalence (BE) biowaiver, based on WHO recommendations and EMEA guidelines. Thus a dissolution requirement on these AMCs would represent a significant advance in the pharmaceutical quality of CHM today.

Herb–drug interactions between Scutellariae Radix and mefenamic acid: Simultaneous investigation of pharmacokinetics, anti-inflammatory effect and gastric damage in rats

ETHNOPHARMACOLOGICAL RELEVANCE Scutellariae Radix (SR), the dried root of Scutellariae baicalensis Georgi, has a lot in common with non-steroidal anti-inflammatory drugs (NSAIDs). Their similarities in therapeutic action (anti-inflammation) and metabolic pathways (phase II metabolisms) may lead to co-administration by patients with the potential of pharmacokinetic and/or pharmacodynamic interactions. The current study aims to investigate the potential interactions between SR and an NSAID, mefenamic acid (MEF), on the overall pharmacokinetic dispositions, anti-inflammatory effects and adverse effects in rats. MATERIALS AND METHODS The current study simultaneously monitored the pharmacokinetic and pharmacodynamic interactions in a single animal. Four groups of Sprague-Dawley rats (n=7 each) received oral doses of a standardized SR extract (300mg/kg, twice daily), MEF (40mg/kg, daily), combination of SR extract and MEF, and vehicle control, respectively, for 5 days. On Day 5, blood samples were collected after first dose over 24h for the determination of (1) plasma concentrations of SR bioactive components, MEF and its metabolites by LC-MS/MS, and (2) prostaglandin E2 (PGE2) production and cyclooxygenase-2 (COX-2) gene expression by ex vivo analyses using LPS-stimulated RAW264.7 macrophage cells, ELISA and real time-PCR. After the rats were sacrificed, stomachs were isolated to assess their gross mucosal damage. Statistical comparisons were conducted using ANOVA and t-test. RESULTS Minimal pharmacokinetic interaction between SR extract and MEF was observed. Co-administration of SR extract and MEF did not significantly alter the plasma concentration-time profile or the pharmacokinetic parameters such as Cmax, AUC0→24, Tmax or clearance. Pharmacodynamic interaction via the COX-2 pathway was observed. The PGE2 level in LPS-stimulated RAW264.7 cells treated with plasma collected from control group over the 24h sampling (AUC0→24[PGE2]) was 191981±8789pg/mlhr, which was significantly reduced to 174,780±6531 and 46,225±1915pg/mlhr by plasma collected from rats administered with SR extract and MEF, respectively. Co-administration of SR extract and MEF further potentiated the PGE2 inhibition, with an AUC0→24[PGE2] of 37013±2354pg/mlhr (p<0.05, compared to SR or MEF group). By analyzing the COX-2 gene expression, SR extract significantly prolonged the COX-2 inhibitory effect of MEF over the 24h (p<0.05). Furthermore, the MEF-induced stomach ulcer after the 5-day treatment, as evidenced by the increased gross ulcer index and sum of lesion length (p<0.05, compared to control), could be alleviated by co-administration with SR extract (p<0.05). CONCLUSIONS Co-administration of SR extract and MEF potentiated the anti-inflammatory effects, alleviated the MEF-induced stomach adverse effect while having minimal pharmacokinetic interactions. Our findings provide insight for combination therapy of SR extract and MEF against inflammatory diseases.

Alterations in the CNS effects of anti-epileptic drugs by Chinese herbal medicines

Introduction: Concomitant use of anti-epileptic drugs (AEDs) and Chinese herbal medicines (CHMs) is increasing globally. However, information summarizing how CHMs might alter the CNS effects of AEDs is lacking. Areas covered: A systematic review of the English-language articles in evidence-based databases was performed. It identified CHMs that interact with AEDs and lead to alterations in the CNS effects of AEDs. This review provides a descriptive summary of the existing information on CHM-induced changes of both the therapeutic and adverse CNS effects of AEDs, including i) anti-epileptic effect, ii) sedative effect, iii) anxiolytic effect and iv) memory impairment effect. The proposed mechanisms behind the interactions are also summarized. Expert opinion: Despite the popularity of both AEDs and CHMs, the availability of information on CHM-AED interactions that could result in altered CNS outcomes is considerably limited. Moreover, there are some insufficiencies in the study designs of the identified reports. More research, including both mechanistic and human studies, with improved study design is necessary to ensure the safety and efficacy of combinational use of AEDs with CHMs.

Brain uptake of bioactive flavones in Scutellariae Radix and its relationship to anxiolytic effect in mice

Scutellariae Radix (SR) and its bioactive flavones elicit a variety of effects in the brain. However, the brain uptake of individual SR flavones and its relationship to the elicited effects after SR administration remain unknown. Moreover, previous studies seldom measured pharmacokinetic and pharmacodynamic outcomes simultaneously. In the current study, the brain uptake of six major SR flavones and the anxiolytic behavior following oral administration of a SR extract at two clinically relevant doses (600 and 1200 mg/kg twice daily) were simultaneously investigated in mice (n = 18 per group). Brain and plasma concentrations of the flavones were measured by LC-MS/MS, while the anxiolytic effect was evaluated using the elevated plus maze. To further investigate the mechanism behind the differential brain uptake of the six SR flavones, these flavones were separately administered to mice at an equivalent molar oral dose (n = 6). The brain tissue bindings of the SR flavones were also measured with the in vitro brain slice method. Our results indicated that all six SR flavones including three aglycons (baicalein, wogonin, and oroxylin A) and three glucuronides (baicalin, wogonoside, and oroxyloside) could pass through the blood-brain barrier, with brain concentrations ranging from 7.9 to 224.0 pmol/g. It provided novel evidence that oroxylin A had the highest brain uptake among the six SR flavones regardless of its limited content in SR extract, in which 3.6-3.9% of the administered oroxylin A dose was present in the brain 6 h postdosing and with a brain-to-plasma ratio of 0.42-0.46. Although SR extract contains flavones that are positive modulators of the benzodiazepine binding site of GABAA receptors (baicalein, wogonin, and baicalin), our behavioral study for the first time indicated that SR extract (a mixture of six flavones) did not elicit significant anxiolytic effect at the studied doses. Oroxylin A also demonstrated the highest brain uptake when the six flavones were separately administered to mice, and the highest affinity to brain tissues in the in vitro tissue binding assay. The high brain uptake of oroxylin A, a GABAA antagonist which had been reported to antagonize diazepam-induced anxiolytic effect, might have suppressed the anxiolytic effects of the other flavones and account for the lack of overall anxiolytic effect of SR extract. The current study illustrates the importance of monitoring pharmacokinetics in a behavioral study, particularly for herbal medicines which consist of multiple components that might have different or even opposite pharmacological effects on the same target.

Influence of mefenamic acid on the intestinal absorption and metabolism of three bioactive flavones in Radix Scutellariae and potential pharmacological impact.

Abstract Context: Mefenamic acid (MEF) and the dried root of Scutellaria baicalensis Georgi (Radix Scutellariae, RS) share a high possibility of combined medication to treat inflammation. Objective: The present study investigates the impact of MEF on absorption/disposition of three major components in RS (baicalein, B; wogonin, W; oroxylin A, OA) and further pharmacological changes. Materials and methods: The apparent permeability (Papp) and percentage of metabolism of B, W and OA at 10 μΜ were measured at the absence/presence of MEF (100 μΜ) in the Caco-2 cell monolayer model. A modified whole blood assay was employed to quantify prostaglandin E2 (PGE2) 4, 6 and 8 h post-oral administration with water suspension of MEF at 40 mg/kg and RS at 200 mg/kg. Results: In the presence of MEF, Papp of B, W and OA were increased from 1.69 ± 0.89 × 10−6, 1.57 ± 0.10 × 10−6 and 3.09 ± 0.70 × 10−6 cm/sec to 5.24 ± 0.27 × 10−6, 6.08 ± 0.19 × 10−6 and 4.13 ± 0.38 × 10−6, whereas their percentage of metabolism was decreased from 72.75 ± 2.44%, 73.27 ± 3.25% and 89.84 ± 2.99% to 21.11 ± 0.69%, 17.90 ± 5.55% and 45.44 ± 3.38%. PGE2 level was much lower in the co-administration group (49.04 ± 2.03 pg/ml) than in the MEF group (73.13 ± 3.03 pg/ml) or RS group (494.37 ± 11.75 pg/ml) 4 h post MEF dosing, suggesting a synergic effect. Discussion and conclusion: Co-administration of MEF and RS could induce potential alterations in their pharmacokinetic profiles and anti-inflammatory effects.

Species difference in the inhibitory potentials of non-steroidal anti-inflammatory drugs on the hepatic sulfation and glucuronidation of bioactive flavonoids: differential observations among common inhibition parameters

Abstract 1. This study elucidated the species differences between rats and humans in the inhibitory potential of drugs against sulfation and glucuronidation, and whether such differences depend on the inhibition parameter adopted. 2. With 14 non-steroidal anti-inflammatory drugs (NSAIDs) as model inhibitors and three flavanoids baicalein, wogonin and oroxylin A as model substrates, three common inhibition parameters percentage of control, IC50 and Ki were determined in rat liver cytosols (RLCs), human liver cytosols (HLCs), rat liver microsomes (RLMs) and human liver microsomes (HLMs). The closeness of the inhibition parameters from rat liver preparations to that from human liver preparations was analyzed by geometric mean fold error (GMFE) and statistical comparisons. 3. The percentage of control in RLC/RLM was not significantly different from that in HLC/HLM, with a GMFE of 0.85 (RLC–HLC) and 1.03 (RLM–HLM); whereas the IC50 and Ki in RLC/RLM were significantly different from that in HLC/HLM. The trend of difference was consistent between IC50 and Ki, where these parameters in RLC and RLM underestimated (GMFE <0.5) and overestimated (GMFE >2) that in HLC and HLM, respectively. 4. In conclusion, the inhibitory potentials of NSAIDs against sulfation and glucuronidation in rats and humans were different and depended on the adopted inhibition parameters.

Modulation of the pharmacokinetics, therapeutic and adverse effects of NSAIDs by Chinese herbal medicines

Introduction: Concomitant use of NSAIDs and Chinese herbal medicines (CHMs) is frequent, yet summarized information on their interactions is lacking. Areas covered: A systematic review of literature in four evidence-based English databases was performed. Articles which reported CHMs altering the pharmacokinetics, therapeutic and adverse effects of NSAIDs were identified and summarized. Such interactions may lead to beneficial, detrimental or no change in outcomes. The current review covers four therapeutic effects of NSAIDs, including: i) anti-inflammatory; ii) analgesic; iii) antiplatelet, cardiovascular and cerebrovascular; and iv) anticancer effects and four adverse effects of NSAIDs, including: i) gastrointestinal ulcer; ii) nephrotoxicity; iii) hepatotoxicity; and iv) antiplatelet effects and bleeding. Expert opinion: While majority of CHMs demonstrated effectiveness in alleviating NSAIDs-induced adverse effects and potentiating the therapeutic effects, this review provides insights for development of CHMs as add-on medications to NSAIDs therapies. However, since limited information was from well-designed clinical trials, the findings are not yet conclusive and more clinical studies are warranted to provide guidance for healthcare professionals. In future, researches on interactions between NSAIDs and CHMs are expected to grow and modern approaches such as pharmacogenomics might enhance the throughput and accuracy of identifying clinically relevant interactions.

Identification and disposition of novel mono-hydroxyl mefenamic acid and their potentially toxic 1-O-acyl-glucuronides in vivo.

Mefenamic acid (MEF) is a widely prescribed non‐steroidal anti‐inflammatory drug that has been found associated with rare but severe cases of hepatotoxicity, nephrotoxicity and gastrointestinal toxicity. The formation of protein‐reactive acylating metabolites such as 1‐O‐acyl‐MEF glucuronide (MEFG) and 3′‐hydroxymethyl‐MEF 1‐O‐acyl‐glucuronide is one proposed cause. In addition to the well‐reported 3′‐hydroxymethyl‐MEF, two mono‐hydroxyl‐MEF (OH‐MEFs) were recently identified in vitro. However, in vivo evidence is lacking and whether these OH‐MEFs would be further glucuronidated to the potentially reactive 1‐O‐acyl‐glucuronides (OH‐MEFGs) is unknown. Utilizing UPLC‐Q‐TOF/MS and LC‐MS/MS, the current study identified, for the first time, four OH‐MEFs and their corresponding OH‐MEFGs from plasma after a single oral administration of MEF (40 mg/kg) to rats, including an OH‐MEF that has not been reported previously. The systemic exposure of these identified metabolites was high, with metabolic to parent AUC0→24h ratios reaching 23–52% (OH‐MEFs) and 8–29% (OH‐MEFGs). These metabolites also had a long systemic exposure time in both single and 5 day multiple oral MEF‐treated rats, with elimination half‐lives between 9 h and > 24 h. In addition to these novel metabolites, the previously reported MEFG was also identified and its systemic exposure was found to be doubled after multiple MEF administrations. These pharmacokinetic results suggest that systemic toxicities caused by the potentially reactive MEFG and OH‐MEFGs could be considerable, especially after repeated MEF treatment. Nevertheless, MEFG and OH‐MEFGs had negligible uptake in the brain, indicating a minimal risk of brain toxicities. Furthermore, an in situ intestinal perfusion study revealed that during MEF absorption, it was extensively metabolized to MEFG while < 5% was metabolized to OH‐MEFs and OH‐MEFGs. Copyright