Comparison of diterpenoid contents and dissolution profiles of selected Andrographis paniculata crude and extract capsules.

INTRODUCTION: Andrographis paniculata (AP) has been approved by the Thai government for the treatment of mild cases of COVID-19 patients. Increasing use of AP products requires quality control to ensure efficacy and safety. At present, there is no requirement for dissolution test of AP products in the Thai Herbal Pharmacopoeia (THP). OBJECTIVE: This work aimed to examine the contents and dissolution profiles of active diterpenoids, andrographolide (AP1), 14-deoxy-11,12-didehydroandrographolide (AP3), neoandrographolide (AP4), and 14-deoxyandrographolide (AP6) in AP capsules available in Thai markets. MATERIALS AND METHODS: Four extract products (EXT. A-D) and three crude powder products (CRD. A-C) were tested for contents by using HPLC-DAD. Dissolution profiles of four diterpenoids were investigated in different media (pH 1.2, 4.5, 6.8, and 0.01 N HCl + SLS) with apparatus II (paddle type). RESULTS: The AP1 contents were 1.99%-2.90% w/w for crude capsules and 2.84%-16.27% w/w for extract capsules. In the dissolution test, the dissolution percentages of four diterpenoids from crude capsules were higher than those from extract capsules except EXT. A. AP1 in most extract products (EXT. B, C, D) was dissolved in all dissolution media at a lower percentage than the other three diterpenoids. EXT. A (aqueous extract) was the only extract capsule showing the amounts of all diterpenoids dissolved in all media >80% in 45 min. CONCLUSION: The study demonstrated that AP1 content in AP products complied with the acceptance criteria in the THP (80%-120%), and the weight variation also met the United States Pharmacopeia (USP) requirements. However, different dissolution profiles of AP products may lead to different bioavailability of diterpenoids and further affect their efficacy.

Clinical Parameters following Multiple Oral Dose Administration of a Standardized Andrographis paniculata Capsule in Healthy Thai Subjects.

Andrographis paniculata has been widely used in Scandinavian and Asian counties for the treatment of the common cold, fever, and noninfectious diarrhea. The present study was carried out to investigate the physiological effects of short-term multiple dose administration of a standardized A. paniculata capsule used for treatment of the common cold and uncomplicated upper respiratory tract infections, including blood pressure, electrocardiogram, blood chemistry, hematological profiles, urinalysis, and blood coagulation in healthy Thai subjects. Twenty healthy subjects (10 males and 10 females) received 12 capsules per day orally of 4.2 g of a standardized A. paniculata crude powder (4 capsules of 1.4 g of A. paniculata, 3 times per day, 8 h intervals) for 3 consecutive days. The results showed that all of the measured clinical parameters were found to be within normal ranges for a healthy person. However, modulation of some parameters was observed after the third day of treatment, for example, inductions of white blood cells and absolute neutrophil count in the blood, a reduction of plasma alkaline phosphatase, and an induction of urine pH. A rapid and transient reduction in blood pressure was observed at 30 min after capsule administration, resulting in a significant reduction of mean systolic blood pressure. There were no serious adverse events observed in the subjects during the treatment period. In conclusion, this study suggests that multiple oral dosing of A. paniculata at the normal therapeutic dose for the common cold and uncomplicated upper respiratory tract infections modulates various clinical parameters within normal ranges for a healthy person.

A Simple and Sensitive LC-MS/MS Method for Determination of Four Major Active Diterpenoids from Andrographis paniculata in Human Plasma and Its Application to a Pilot Study.

Andrographis paniculata contains four major active diterpenoids, including andrographolide (1), 14-deoxy-11, 12-didehydroandrographolide (2), neoandrographolide (3), and 14-deoxyandrographolide (4), which exhibit differences in types and/or degrees of their pharmacological activity. Previous pharmacokinetic studies in humans reported only the parameters of compound 1 and its analytical method in human plasma. The purpose of this study was to develop a simple, sensitive, and selective liquid chromatography tandem-mass spectrometry technique for the simultaneous determination of all four major active diterpenoids in the A. paniculata product in human plasma. These four diterpenoids in plasma samples were extracted by a simple protein precipitation method with methanol and separated on a Kinetex C18 column using a gradient system with a mobile phase of acetonitrile and water. The liquid chromatography tandem-mass spectrometry was performed in the negative mode, and the multiple reaction monitoring mode was used for the quantitation. The method showed a good linearity over a wide concentration range of 2.50-500 ng/mL for 1 and over the range of 1.00-500 ng/mL for the other diterpenoids with a correlation coefficient R(2) > 0.995. The lower limit of quantification of 1 was found to be 2.50 ng/mL, while those of the other diterpenoids were 1.00 ng/mL. The intraday and interday accuracy (relative error) ranged from 0.03 % to 10.03 %, and the intraday and interday precisions (relative standard deviation) were in the range of 2.05-9.67 %. The extraction recovery (86.54-111.56 %) with a relative standard deviation of 2.78-8.61 % and the matrix effect (85.15-112.36 %) were within the acceptance criteria. Moreover, these four major active diterpenoids were stable in plasma samples at the studied storage conditions with a relative error ≤-9.79 % and a relative standard deviation ≤ 9.26 %. Hence, this present method was successfully validated and used in the pilot study to determine the pharmacokinetic parameters of all four major active diterpenoids in human plasma after multiple oral doses of the A. paniculata product were administered to a healthy, Thai female volunteer.

Effect of CYP3A5 genotypes on the pharmacokinetics of carbamazepine when used as monotherapy or co-administered with phenytoin, phenobarbital or valproic acid in Thai patients.

PURPOSE: To determine the effects of CYP3A5 polymorphisms on carbamazepine (CBZ) pharmacokinetic parameters when CBZ is used either as monotherapy or co-administered with phenytoin (PHT), phenobarbital (PB) or valproic acid (VPA). METHODS: Retrospective data were collected from an electronic database and medical records. Blood samples were obtained and drug concentrations analyzed as a part of routine therapeutic drug monitoring (TDM). Screening for wild-type CYP3A5*1 and CYP3A5*3 single nucleotide polymorphism (rs776746) by allelic discrimination assay using real-time polymerase chain reaction technique (real-time PCR) was performed. Pharmacokinetic parameters of CBZ; clearance and dose-adjusted CBZ levels in patients with different genotypes were calculated and compared. RESULTS: Of the 70 patients assessed, 8 (11%) patients were homozygous CYP3A5*1/*1, 28 (40%) patients were heterozygous CYP3A5*1/*3, and 34 (49%) patients were homozygous CYP3A5*3/*3. The CBZ clearance and dose-adjusted CBZ levels did not significantly differ between patients with CYP3A5*1 and CYP3A5*3 alleles when CBZ was used as monotherapy. For patients who used CBZ in combination with an enzyme-inducing antiepileptic drug (AED: PHT or PB), individuals carrying the CYP3A5*1 allele (CYP3A5 expressers) showed a trend of having higher CBZ clearance and lower dose-adjusted CBZ level as compared to individuals carrying the CYP3A5*3 allele, even though no statistical significance was recorded. Nevertheless, it was observed that AEDs significantly increased CBZ clearance only in patients carrying the active CYP3A5*1 allele. CONCLUSIONS: When CBZ was used in combination with enzyme-inducing AED, CYP3A5 expressers yielded a trend toward greater susceptibility to change in CBZ clearance and showed lower dose-adjusted CBZ levels compared to CYP3A5 non-expressers. The dosage regimen should be adjusted accordingly to gain a better clinical outcome.This article is open to POST-PUBLICATION REVIEW. Registered readers (see "For Readers") may comment by clicking on ABSTRACT on the issue's contents page.

A validated LC-MS/MS method for clinical pharmacokinetics and presumptive phase II metabolic pathways following oral administration of Andrographis paniculata extract.

Andrographis paniculata, a medicinal plant in Thailand national list of essential medicines, has been proposed for treatment of patients with mild to moderate coronavirus disease 2019. This study aims to develop a highly selective and sensitive liquid chromatography triple quadrupole tandem mass spectrometry method for quantitative determination of major diterpenoids in plasma and urine with application in pharmacokinetics. Chromatographic separation was performed on C18 column using a gradient mobile phase of water and acetonitrile. Mass spectrometry was analyzed using multiple reaction monitoring with negative ionization mode. This validated analytical method was very sensitive, less time consuming in analysis, and allowed the reliability and reproducibility on its application. The clinical pharmacokinetics was evaluated after single oral administration of A. paniculata extract (calculated as 60 mg of andrographolide). The disposition kinetics demonstrated that major diterpenoids could enter into systemic circulation, but they are mostly biotransformed (phase II) into conjugated glucuronide and sulfate metabolites. These metabolites are predominantly found in plasma and then extremely eliminated, in part through urinary excretion. The successful application of this analytical method supports its suitable uses in further clinical benefits after oral administration of A. paniculata.

Comparative pharmacokinetics and safety evaluation of high dosage regimens of Andrographis paniculata aqueous extract after single and multiple oral administration in healthy participants.

Background: The prolonged situation of the COVID-19 pandemic, with the emergence of new variants of SARS-CoV-2, not only imposes a financial burden on healthcare supports but also contributes to the issue of medication shortages, particularly in countries with limited access to medical resources or developing countries. To provide an alternative therapeutic approach during this crisis, there is an increasing research that has investigated the potential uses of Andrographis paniculata in supporting the application of herbal medicine for COVID-19. Purpose: This study aimed to investigate the safety profiles and clinical pharmacokinetics, specifically focusing on dose proportionality of the four major active diterpenoids of Andrographis paniculata aqueous extract following oral administration of two different high doses of andrographolide. Methods: The participants received the aqueous extract capsules equivalent to 60 or 120 mg of andrographolide; and as multiple doses administered three times daily, calculated as 180 or 360 mg/day of andrographolide. Safety evaluation was assessed following the oral administration of the multiple doses. Results: The results indicated a dose-dependent effect observed between the respective two doses. A twofold increase in the dose of the extract demonstrated twofold higher plasma concentrations of the four major parent compounds; 1) andrographolide, 2) 14-deoxy-11, 12-didehydroandrographolide, 3) neoandrographolide, and 4) 14-deoxyandrographolide, as well as their conjugated metabolites. The observed diterpenoids are biotransformed partly through a phase II metabolic pathway of conjugation, thus reducing in the parent compounds in the plasma and existing the majority as conjugated metabolites. These metabolites are then excreted through the hepatobiliary system and urinary elimination. For the results of the safety evaluation, the occasional adverse events experienced by individuals were of mild intensity, infrequent in occurrence, and reversible to the normal baseline. Safety consideration should be given to the individual patient's pertinent health conditions when using this extract in patients with hepatic or kidney dysfunction. Clinical Trial Registration: https://www.thaiclinicaltrials.org/show/TCTR20210201005; Identifier: TCTR20210201005.

A comprehensive review on disposition kinetics and dosage of oral administration of Andrographis paniculata, an alternative herbal medicine, in co-treatment of coronavirus disease.

Coronavirus disease 2019 (COVID-19) is a present global health crisis that is driving the investigation of alternative phytomedicines for antiviral purposes. The evidence suggests that Andrographis paniculata crude or extract is a promising candidate for treating symptoms of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This review aims to consolidate the available reports on the disposition kinetics of andrographolide, a main active component of A. paniculata. The second objective of this review is to summarize the available reports on an appropriate oral dosage for the use of andrographolide in upper respiratory tract infections (URTIs) and other viral infectious diseases. The data were collected from the literature on absorption, distribution, biotransformation, and excretion of andrographolide, and information was also obtained from scientific databases about the use of A. paniculata. The finding of this review on pharmacokinetics indicates that andrographolide is slightly absorbed into the blood circulation and exhibits poor oral bioavailability, whereas its distribution process is unrestricted. In the termination phase, andrographolide preferentially undergoes biotransformation partly through phase I hydroxylation and phase II conjugation, and it is then eliminated via the renal excretion and hepatobiliary system. The key summary of the recommended dosage for andrographolide in uncomplicated URTI treatment is 30 mg/day for children and 60 mg/day for adults. The dose for adult patients with pharyngotonsillitis could be increased to 180 mg/day, but not exceed 360 mg/day. Co-treatment with A. paniculata in concert with the standard supportive care for influenza reduced the severity of symptoms, shortened treatment duration, and decreased the risk of developing post-influenza complications. The recommended starting dose for use in patients with mild COVID-19 is 180 mg/day of andrographolide, based on the dose used in patients experiencing a URTI with inflammation. This review is not only applicable for evaluating the appropriate doses of andrographolide for antiviral treatments but also encourages future research evaluating the effectiveness of these recommended dosages during the COVID-19 pandemic.

The impact of dosage of sustained-release formulation on valproate clearance and plasma concentration in psychiatric patients: analysis based on routine therapeutic drug monitoring data.

Pharmacokinetic parameters were compared between 2 dosages of valproic acid (VPA) sustained-release (SR) formulation in psychiatric patients. A total of 66 psychiatric patients (21 women and 45 men; age range, 18-60 years) receiving 500 mg/d (n = 28) or 1000 mg/d (n = 38) of VPA SR for at least 4 weeks were recruited into the study. A 5-mL blood sample was collected into a plain tube and immediately centrifuged for plasma. Separation of free VPA was further done using Centrifree micropartition devices. Both total and free VPA concentrations (C(total) and C(free)) were analyzed by TDx analyzer with fluorescence polarization immunoassay technique. The patients' characteristics and pharmacokinetic parameters were compared between the 2 dosage groups using independent t test or χ² test where appropriate. The results show that the increment in C(total) (mg/mL) for every milligram-per-kilogram increment in dosage was decreased from 7 ± 3 to 4 ± 1 (mg/L) / (mg/kg) when the total VPA clearance (CL(total)) increased from 6.1 ± 2.6 to 9.0 ± 3.1 mL/kg per hour with the increasing dose in the 500 mg/d and 1000 mg/d groups, respectively (P < 0.05). The increment in C(free) [0.6 ± 0.3 vs 0.5 ± 0.2 (mg/L) / (mg/kg)] and CL(free) (80.4 ± 41.5 vs 92.2 ± 47.6 ml/kg per hour) were not significantly different. Owing to the saturation of protein binding, percent free VPA was significantly increased from 8 ± 3 to 11 ± 3 when the dose was increased from 500 to 1000 mg/d (P < 0.05). In conclusion, an increase in the VPA dose resulted in a disproportional increase between dosage and C(total), whereas a proportional increase between dosage and C(free) still existed. Therefore, our study suggests that the therapeutic range of C(free) is 4 to 12 mg/L based on the therapeutic range of C(total) (45-100 mg/L) for general psychiatric conditions.

Comparison between the effect of omeprazole and rabeprazole on the antiplatelet action of clopidogrel.

BACKGROUND: Emerging data suggests that several proton pump inhibitors (PPIs), including omeprazole, might interfere with the antiplatelet action of clopidogrel. However, there is a lack of data for rabeprazole. This study aimed to investigate and compare the impact of omeprazole and rabeprazole on the antiplatelet action of clopidogrel among patients with coronary artery disease (CAD). METHODS AND RESULTS: A prospective, randomized, open-labeled study was conducted among 87 CAD patients receiving clopidogrel and aspirin. Forty three and 44 patients were randomized to receive omeprazole 20 mg and rabeprazole 20 mg once daily, respectively, for at least 2 weeks. Adenosine 5-diphosphate 20 µmol/L-induced platelet aggregation was performed before and after PPIs treatment. Mean maximal platelet aggregation (MPA) before and after PPIs treatment of both groups were compared. At baseline, there were no significant differences in the mean MPA between the omeprazole and rabeprazole groups (40.68 ± 18.82% vs 36.42 ± 21.39%; P=0.326). After a 2-week treatment with PPIs, the mean MPA in both groups significantly increased from baseline and there were no differences between the omeprazole and rabeprazole groups (55.73 ± 19.66% vs 48.46 ± 18.80%; P=0.141). CONCLUSIONS: Both omeprazole and rabeprazole decreased the antiplatelet effect of clopidogrel. Use of these agents resulted in a similar degree of interference on clopidogrel's action, as measured by ADP-induced platelet aggregation.

Higher therapeutic plasma oxypurinol concentrations might be required for gouty patients with chronic kidney disease.

BACKGROUND: Lower dosages of allopurinol are recommended to avoid toxicity in gout patients with impaired renal function. This often has resulted in inadequate control of hyperuricemia. The optimum therapeutic range of plasma oxypurinol concentrations in gout patients with chronic kidney disease has never been investigated. This study was performed to examine the relationships between plasma oxypurinol concentrations and the changes in serum urate level and renal function after taking a standard dose of allopurinol, 300 mg daily, in gout patients with renal insufficiency. PATIENTS AND METHODS: The study was conducted in 27 gout patients with renal insufficiency in a rheumatology clinic at the Rajvithi Hospital, Bangkok. Both new and current patients, after they discontinued allopurinol completely for 4 weeks, were treated with allopurinol 300 mg daily for 6 weeks. Blood samples were collected immediately before and 5 hours after the studied dose had been taken. Serum urate levels and renal function were recorded before and after the 6 weeks of allopurinol treatments. RESULTS: Most patients receiving allopurinol 300 mg/d had their plasma oxypurinol concentrations higher than the proposed therapeutic range for patients with normal renal function. There were significant relationships between changes in serum urate level with both trough and fifth-hour oxypurinol concentrations (R = 0.42, P = 0.002 and R = 0.27, P = 0.007, respectively). Higher plasma oxypurinol concentrations resulted in a higher percentage of patients who could meet the therapeutic treatment goal. No serious side effect and no significantly change in creatinine clearance were observed indicating that high levels of oxypurinol did not appear to relate to higher prevalence of adverse reaction. CONCLUSIONS: Higher percentages of patients could meet the treatment goal when their plasma oxypurinol concentrations were higher than the proposed therapeutic range for patients with normal renal function.

Correlation of the pharmacokinetic parameters of amikacin and ceftazidime.

BACKGROUND AND OBJECTIVES: Ceftazidime and amikacin are often prescribed concomitantly to treat infections caused by Gram-negative bacteria. Their physicochemical properties are quite similar. Both drugs are highly soluble in water, have low plasma protein binding and are >95% excreted unchanged by the kidney via glomerular filtration. Their pharmacokinetic parameters are therefore expected to correlate. This study was performed to explore the correlation between the pharmacokinetic parameters of these two drugs. PATIENTS AND METHODS: Patients at Phramongkutklao Hospital, Bangkok, Thailand, who met the inclusion criteria participated in the study. They all received ceftazidime and amikacin concomitantly to treat their infections. After steady-state conditions had been reached, two blood samples were collected during the elimination phase of both drugs. Plasma drug concentrations were analysed and the pharmacokinetic parameters of each drug were calculated. The pharmacokinetic parameters that were examined included total drug clearance (CL), the elimination rate constant (k(e)), the elimination half life (t(1/2)) and the volume of distribution (V(d)). The correlations of the pharmacokinetic parameters of amikacin and ceftazidime were determined using regression analysis. RESULTS: Regression analysis showed that the pharmacokinetic parameters of ceftazidime and amikacin were highly correlated. The correlation coefficients (r) of CL, k(e), t(1/2) and V(d) of the two drugs were 0.966, 0.943, 0.888 and 0.671, respectively. The correlation between amikacin clearance and ceftazidime clearance was higher than the correlation between either amikacin or ceftazidime clearance and creatinine clearance, for which the r values were 0.647 and 0.661, respectively. CONCLUSIONS: The pharmacokinetic parameters of ceftazidime and amikacin were highly correlated. Knowledge of the pharmacokinetic parameters of one of these drugs can be used to predict the pharmacokinetic parameters of the other drug.

Steady-state serum phenytoin concentrations after nasogastric tube administration of immediate-release phenytoin tablets and extended-release phenytoin capsules: an open-label, crossover, clinical trial.

BACKGROUND: When phenytoin is prescribed for administration via nasogastric tube, immediate-release OR) phenytoin tablets are crushed before use and extended-release (ER) phenytoin capsules are opened and only the granules are used. However, it is unknown whether the same dose of these 2 different formulations will result in the same steady-state serum phenytoin concentration. OBJECTIVE: The aim of this study was to determine whether ER phenytoin capsules can be used interchangeably with IR phenytoin tablets for prophylaxis of posttraumatic seizures. METHODS: Inpatients at the neurosurgical ward at Prasat Neurological Institute, Bangkok, Thailand, between October 2004 and October 2005 were enrolled in the study. All patients were initially prescribed IR phenytoin tablets 300 mg/d as a maintenance dose for prophylaxis of posttraumatic seizures. The serum phenytoin concentration was measured after ≥5 days of treatment with IR phenytoin tablets 300 mg/d (two 50-mg tablets every 8 hours) that had been crushed before being administered concomitantly with a blenderized diet through the nasogastric tube. Without a washout period, the dosage form was changed to ER phenytoin capsules (three 100-mg capsules QD). The capsules were opened and the contents were administered concomitantly with the blenderized diet through the nasogastric tube for ≥5 days. The serum phenytoin concentration was again determined. The patients were closely monitored for seizures and adverse events (AEs). RESULTS: Thirty-three patients enrolled in the study and 17 (10 women, 7 men; mean [SD] age, 62.94 [15.94] years [range, 18-89 years]) completed the study. The mean (SD) serum phenytoin concentrations after administration of phenytoin tablets and capsules were 6.03 (5.92) µg/mL and 3.80 (2.71) µg/mL, respectively (P = 0.019). The mean serum phenytoin concentrations, adjusted for low serum albumin concentrations after administration of tablets and capsules, were calculated and reported to be 10.33 (11.60) µg/mL and 6.28 (4.76) µg/mL, respectively (P = 0.035). The maximum phenytoin metabolic rate (Vmax) (assuming the substrate concentration at which the rate of metabolism is one half Vmax = 4 mg/L) after the administration of phenytoin tablets and capsules was 8.37 (2.42) mg/kg · d(-1) and 10.38 (6.48) mg/kg · d(-1), respectively. These values were not significantly different. All patients were seizure-free and no AEs were observed. CONCLUSION: The steady-state serum phenytoin concentration was significantly lower with ER phenytoin capsules 300 mg/d than IR phenytoin tablets 300 mg/d administered via nasogastric feeding tube concomitantly administered with a blenderized diet in these neurosurgical patients. Key words: phenytoin nasogastric tube feeding extended-release capsule immediate-release tablet.

Preliminary study of the association between the elimination parameters of phenytoin and phenobarbital.

BACKGROUND: Therapeutic drug monitoring is essential for both phenytoin and phenobarbital therapy given their narrow therapeutic indexes. Nevertheless, the measurement of either phenytoin or phenobarbital concentrations might not be available in some rural hospitals. Information assisting individualized phenytoin and phenobarbital combination therapy is important. This study's objective was to determine the relationship between the maximum rate of metabolism of phenytoin (Vmax) and phenobarbital clearance (CLPB), which can serve as a guide to individualized drug therapy. METHODS: Data on phenytoin and phenobarbital concentrations of 19 epileptic patients concurrently receiving both drugs were obtained from medical records. Phenytoin and phenobarbital pharmacokinetic parameters were studied at steady-state conditions. The relationship between the elimination parameters of both drugs was determined using simple linear regression. RESULTS: A high correlation coefficient between Vmax and CLPB was found [r=0.744; p<0.001 for Vmax (mg/kg/day) vs. CLPB (L/kg/day)]. Such a relatively strong linear relationship between the elimination parameters of both drugs indicates that Vmax might be predicted from CLPB and vice versa. CONCLUSIONS: Regression equations were established for estimating Vmax from CLPB, and vice versa in patients treated with combination of phenytoin and phenobarbital. These proposed equations can be of use in aiding individualized drug therapy.

Effects of CYP2D6 and CYP3A5 polymorphisms on tamoxifen and its metabolites in Thai breast cancer patients.

PURPOSE: This study aimed to determine the effects of CYP2D6 and CYP3A5 polymorphisms on the levels of tamoxifen (TAM) and its metabolites in the plasma of breast cancer patients. The protocol was designed to test the associations between CYP2D6, CYP3A5 genotypes and phenotypes (extensive metabolizer [EM], intermediate metabolizer [IM] and poor metabolizer [PM]) and TAM, N-desmethyl tamoxifen (NDMT), endoxifen (END) and 4-hydroxytamoxifen (4OHT) concentrations. PATIENTS AND METHODS: One hundred and thirty-four Thai breast cancer patients from the Thai Tamoxifen Project undergoing TAM treatment who met the inclusion/exclusion criteria were recruited. Plasma samples were assessed for the concentrations of TAM and its metabolites using high-performance liquid chromatography. The data are presented as actual values and metabolic ratios (MR). The hypotheses were tested using Kruskal-Wallis or Mann-Whitney U test, including the simple main effects analysis. RESULTS: The patients had stage 0-IV breast cancer. The mean age and body mass index were 51.6±11.6 years and 24.0±4.3, respectively. Also, 53.0% of them were premenopausal, 10.4% were perimenopausal and 36.6% were postmenopausal, while 23.1% were CYP2D6-EM/CYP3A5-EM and 20.9% carried only CYP2D6 and CYP3A5 incomplete alleles. The median concentrations of TAM, NDMT, END and 4OHT were 374.7 (interquartile range [IQR] 230.2) ng/mL, 1,064.9 (IQR 599.6) ng/mL, 54.5 (IQR 52.5) ng/mL and 5.0 (IQR 3.1) ng/mL, respectively. MR (TAM-NDMT) and MR (NDMT-END) were statistically different (p=0.013 and p=0.014, respectively), while MR (4OHT-END) was not statistically different within the CYP2D6 phenotype (p=0.594). MR (TAM-4OHT) was not statistically different within the CYP2D6 phenotype (p=0.079), but it was potentially different from CYP3A5-PM (p=0.056). None of the MR was statistically different within the CYP3A5 phenotype. CONCLUSION: CYP2D6 polymorphisms appear to affect END concentration through an NDMT subpathway and potentially affect 4OHT concentrations through a 4OHT subpathway in CYP3A5-PM group.

Prevalence of CYP2D6*2, CYP2D6*4, CYP2D6*10, and CYP3A5*3 in Thai breast cancer patients undergoing tamoxifen treatment.

BACKGROUND: Tamoxifen (TAM) is used in breast cancer treatment, but interindividual variabilities in TAM-metabolizing enzymes exist and have been linked to single nucleotide polymorphisms in the respective encoding genes. The different alleles and genotypes of these genes have been presented for Caucasians and Asians. This study aimed to explore the prevalence of the incomplete functional alleles and genotypes of the CYP2D6 and CYP3A5 genes in Thai breast cancer patients undergoing TAM treatment. PATIENTS AND METHODS: In total, 134 Thai breast cancer patients were randomly invited to join the Thai Tamoxifen Project. Their blood samples were collected and extracted for individual DNA. The alleles and genotypes were determined by real-time polymerase chain reaction with TaqMan(®) Drug Metabolism Genotyping Assays. RESULTS: The patients were aged from 27.0 years to 82.0 years with a body mass index range from 15.4 to 40.0, with the majority (103/134) in the early stage (stages 0-II) of breast cancer. The median duration of TAM administration was 17.2 months (interquartile range 16.1 months). Most (53%) of the patients were premenopausal with an estrogen receptor (ER) and progesterone receptor (PR) status of ER+/PR+ (71.7%), ER+/PR- (26.9%), ER-/PR+ (0.7%), and ER-/PR- (0.7%). The allele frequencies of CYP2D6*1, CYP2D6*2, CYP2D6*4, CYP2D6*10, CYP3A5*1, and CYP3A5*3 were 72.9%, 3.2%, 1.1%, 22.8%, 37.3%, and 62.7%, respectively, while the genotype frequencies of CYP2D6*1/*1, CYP2D6*1/*2, CYP2D6*2/*2, CYP2D6*4/*4, CYP2D6*1/*10, CYP2D6*2/*10, CYP2D6*4/*10, CYP2D6*10/*10, CYP3A5*1/*1, CYP3A5*1/*3, and CYP3A5*3/*3 were 9.7%, 2.2%, 3.7%, 1.5%, 15.7%, 9.7%, 3.7%, 53.7%, 13.4%, 47.8%, and 38.8%, respectively. CONCLUSION: The majority (97.8%) of Thai breast cancer patients undergoing TAM treatment carry at least one incomplete functional allele, including 20.9% of the patients who carry only incomplete functional alleles for both the CYP2D6 and CYP3A5 genes. This research indicates the high prevalence of these defective alleles that are involved in TAM-metabolic pathways that might further affect TAM treatment.

Andrographis paniculata: Dissolution investigation and pharmacokinetic studies of four major active diterpenoids after multiple oral dose administration in healthy Thai volunteers.

ETHNOPHARMACOLOGICAL RELEVANCE: Andrographis paniculata is included in 'The National List of Essential Herbal Drugs A.D. 1999' of Thailand as an herbal drug for the treatment of common cold symptoms and non-infectious diarrhea. The therapeutic activities of A. paniculata are attributed to four major active diterpenoids: andrographolide (1), 14-deoxy-11, 12-didehydroandrographolide (2), neoandrographolide (3), and 14-deoxyandrographolide (4). However, the pharmacokinetic studies in humans of this plant were performed after a single oral dose administration and reported the parameters related to be of only 1. AIM OF THE STUDY: This study aims to determine the pharmacokinetic parameters of four major active diterpenoids after multiple oral dose administration of A. paniculata capsules in healthy volunteers. The dissolution testing of these four diterpenoids was also performed. MATERIALS AND METHOD: The dissolution testing of four major active diterpenoids was conducted in pH 1.2, pH 4.5, and pH 6.8 for 10-100min. The pharmacokinetic study of these active diterpenoids was designed as an open-label, multiple oral dose administration of A. paniculata capsules in 20 healthy Thai volunteers at 1:1 ratio of female and male. Each volunteer was given four A. paniculata capsules each time which contained 1, 2, 3, and 4 in the quantities of 32.64, 5.40, 3.60, and 3.84mg, respectively, three times a day for three consecutive days. On the fourth day, after the first dose of the day was administered, blood samples were collected at the predefined time points. The validated LC-MS/MS method was used to simultaneously determine the concentrations of these diterpenoids in the human plasma samples. The pharmacokinetic parameters of each active diterpenoid were determined. RESULTS: All four major active diterpenoids have been completely dissolved in the simulated pH of gastrointestinal tract within 60min of dissolution. The dissolution profiles were found to be highest in pH 6.8 and lowest in pH 1.2, especially for 3. In the pharmacokinetic study, although 1 was administered at the highest dose among these four diterpenoids, 2 exhibited the highest maximum concentrations (Cmax) of 44.89ng/mL and area under the plasma concentration-time curve (AUC) of 128.17h×ng/mL. Compound 1 had the second highest Cmax and AUC as 32.41ng/mL and 55.23h×ng/mL, respectively. The relative systemic exposure, represented by the dose normalized AUC [(h×ng/mL)/(mg/kg)], of 2 was approximately 14 times higher than that of 1, while those of 3 and 4 were approximately 1.5 and 1.6 times higher, respectively. Cmax, AUC, apparent volume of distribution, and apparent clearance of 2 were found to be significant difference between female and male. However, when these parameters were calculated as dose normalized basis, no statistically significant difference was found. CONCLUSION: The four major active diterpenoids in the A. paniculata capsules were soluble in all studied dissolution media. The pharmacokinetic parameters of these active diterpenoids in the present study could be applied for dose optimization of A. paniculata product in order to obtain good therapeutic efficacy and reduce the possible side effects that may occur from different active diterpenoids in this medicinal plant.

Pharmacokinetic and pharmacodynamic variation associated with VKORC1 and CYP2C9 polymorphisms in Thai patients taking warfarin.

We investigated the influence of genetic polymorphisms of CYP2C9 and VKORC1 genotypes on the pharmacokinetics and pharmacodynamics of warfarin and established an equation for predicting the maintenance dose of warfarin in the Thai population using genetic and non-genetic factors. The CYP2C9*2, CYP2C9*3, VKORC1 C1173T and VKORC1 G-1639A genotypes were detected by realtime PCR using fluorogenic hybridization probes. The associations between genetic and demographic factors with respect to warfarin dosage were analyzed. CYP2C9 polymorphisms affect warfarin metabolism as shown by a significant difference in warfarin clearance, whereas VKORC1 genotypes cause a significant difference in warfarin sensitivity index (INR:Cp). The mean weekly warfarin dose was significantly different among different VKORC1 and CYP2C9 genotypes. Patients with the VKORC1 BB haplotype and CYP2C9*1/*1 required about twice the warfarin dose compared to those with the VKORC1 AA haplotype and CYP2C9*1/*1. Using stepwise multiple linear regression, clinical factors (age and weight) and genetic factors (CYP2C9 and VKORC1) could explain about 53.8% of the variance of the warfarin maintenance dose. CYP2C9 and VKORC1 genotypes played an important role in the inter-individual variation in warfarin maintenance dose in a Thai population.