Pharmacokinetic and haemodynamic interactions between amlodipine and losartan in human beings

A single-dose, randomized, crossover bioequivalence study of levamlodipine besilate tablets in healthy subjects

Levamlodipine, the levorotatory form of amlodipine racemate, has a blood pressure-lowering effect that is twice that of the racemate. The study aims to establish a foundation for the clinical application of the test drug by conducting a phase I clinical bioequivalence trial, comparing its bioequivalence and safety with the reference drug in healthy Chinese subjects. Recruiting 26 healthy subjects for separate bioequivalence trials in both fasting and fed conditions. The subjects will orally administer 2.5-mg test drug and 5-mg reference drug. A chiral method was used for bioanalytics and liquid chromatography-tandem mass spectrometry was employed to quantify the (S)-amlodipine concentrations at various time points after administration. In fasting condition, the geometric mean ratios (GMRs) for the primary pharmacokinetic parameters Cmax, AUC0-t, and AUC0-∞ are 100.24%, 103.63%, and 103.24%, respectively. The 90% confidence intervals (CIs) fall within the range of 80-125%, satisfying the established bioequivalence criteria. Similarly, upon oral administration of the drugs in the fed condition, the GMRs for Cmax, AUC0-t, and AUC0-∞ are 96.48%, 99.90%, and 99.62%, respectively. The corresponding 90% CIs are within the limits of 80-125%, meeting the predefined bioequivalence standards. Furthermore, both drugs exhibited favorable safety profiles. The results show that the two drugs are bioequivalent in healthy Chinese subjects under both fasting and fed conditions. The two drugs both had similar PK parameters and good safety.

Combination of losartan and puerarin induced pharmacokinetic interaction in hypertension rats and enhances the antihypertensive effect of losartan

The co-administration of losartan and puerarin in hypertension rat models was investigated aiming to evaluate their interaction and potential mechanism.Hypertension rat models were established with N (omega)-nitro-L-arginine methyl ester and the pharmacokinetics and antihypertensive effect of losartan were analyzed in normal and hypertension rats. In vitro, the metabolic stability of losartan was evaluated in rat liver microsomes, and the effect of puerarin on the activity of CYP2C9 and 3A4 was assessed in human liver microsomes.Puerarin significantly changed the pharmacokinetic profiling of losartan in hypertension rats behavior with the increasing AUC, AUMC, C_max, and prolonged t_1/2. The antihypertensive effect of losartan was enhanced by the co-administration of puerarin, which reduced the systolic blood pressure and diastolic blood pressure below normal levels. In vitro, puerarin significantly improved the metabolic stability of losartan with a reduced intrinsic clearance rate. Puerarin also showed significant inhibitory effects on the activity of CYP2C9 and 3A4 with the IC₅₀ of 17.15 and 7.69 μM, respectively.Losartan co-administered with puerarin increased the system exposure and metabolic stability of losartan and enhanced its antihypertensive effect. The inhibition of CYP2C9 and 3A4 by puerarin was the potential mechanism mediating their interaction.

Evaluation of Potential Herb-Drug Interactions Between Shengmai Injection and Losartan Potassium in Rat and In Vitro

Aim: The present study aimed to explore the potential herb-drug interactions (HDI) between Shengmai injection (SMI) and losartan potassium (LOS) based on the expression profiles of cytochromes P450 (CYP450) and drug transporters in rat and in vitro. Methods: Different concentrations of SMI were used to explore the influence of SMI on the antihypertensive efficacy of LOS in the hypertension rat model established by N (omega)-nitro-L-arginine methyl ester (L-NAME) for 4 weeks. Subsequently, the serum concentration levels of LOS and losartan carboxylic acid (EXP3174) were determined by Liquid Chromatography Mass Spectrometry (LC-MS) and pharmacokinetic analysis. Human liver microsomes, human multidrug resistance protein 1 (MDR1/P-gp), and breast cancer resistance protein (BCRP) vesicles, human embryonic kidney 293 cell line with stable expression of the organic anion transporting polypeptide 1B1 (HEK293-OATP1B1 cells) and mock-transfected HEK293 (HEK293-MOCK) cells were used to verify the effects of SMI on CYP450 enzymes and drug transporters in vitro. Results: Low, medium, and high concentrations of SMI increased the antihypertensive efficacy of LOS to varying degrees. The high dose SMI increased the half-life (t _1/2 ), the maximum plasma concentration (C _max), the area under the plasma concentration-time curve (AUC) from time zero to the time of the last measurable plasma concentration (AUC _0-t ), AUC from time zero to infinity (AUC _0-∞ ), and mean residence time (MRT) values of LOS and decreased its apparent volume of distribution (Vd) and clearance (CL) values. The AUC _0-t , AUC _0-∞ , and MRT of LOS were increased, whereas the CL was decreased by the medium concentration of SMI. In addition, the high, medium, and low doses of SMI increased the relative bioavailability (Frel) of LOS. SMI exhibited no significant effects on the pharmacokinetics of EXP3174. In vitro, SMI exhibited different suppressive effects on the enzyme activity levels of CYP1A2 (6.12%), CYP2B6 (2.72%), CYP2C9 (14.31%), CYP2C19 (12.96%), CYP2D6 (12.26%), CYP3A4 (3.72%), CYP2C8 (10.00-30.00%), MDR1 (0.75%), OATP1B1(2.03%), and BCRP (0.15%). Conclusion: In conclusion, SMI improved the antihypertensive efficacy of LOS in the L-NAME-induced hypertension rat model by increasing the concentration of LOS, while leaving the concentration of EXP3174 intact. SMI affected the pharmacokinetic properties of LOS by decreasing the elimination of LOS. These effects might partly be attributed to the inhibition of the activities of CYP3A4, CYP2C9, and of the drug transporters (P-gp, BCRP, and OATP1B1) by SMI, which need further scrutiny.

Pharmacokinetics of a Fixed-Dose Combination of Amlodipine/Losartan and Chlorthalidone Compared to Concurrent Administration of the Separate Components

Hypertension is more effectively treated with coadministration of 2 or more antihypertensive drugs than with high-dose monotherapy. Therefore, calcium channel blockers, angiotensin II receptor blockers, and thiazides are coadministered to treat hypertension. The objective of this study was to compare the pharmacokinetic (PK) profiles of HCP1401, a fixed-dose combination of amlodipine 5 mg, losartan 100 mg, and chlorthalidone 25 mg, with the separate components (loose combination) of amlodipine/losartan 5/100 mg and chlorthalidone 25 mg. A randomized, open-label, single-dose, 2-way crossover study was conducted. Blood samples for amlodipine and chlorthalidone were collected for up to 144 hours after dosing, whereas those for losartan were collected up to 48 hours after dosing. The PK parameters of these drugs were calculated using a noncompartmental method. Sixty subjects completed the study. The geometric mean ratios and 90% confidence intervals of maximum plasma concentration and area under the concentration-time curve to the last measurable point for amlodipine, losartan, and chlorthalidone were within the conventional bioequivalence range of 0.80 to 1.25. There were no clinically significant changes in safety assessments, and the treatments were well tolerated. The PK characteristics and tolerability profiles of a single oral FDC of amlodipine, losartan, and chlorthalidone were equivalent to those of individual tablets in a loose combination.

Plasma Trough Concentrations of Antihypertensive Drugs for the Assessment of Treatment Adherence: A Meta-Analysis

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Biochemical drug screening by liquid chromatography-tandem mass spectrometry in plasma is an accurate method for the quantification of plasma concentrations of antihypertensive medications in patients with hypertension. Trough concentrations could possibly be used as drug-specific cutoff values in the biochemical assessment of (non-)adherence. We performed a literature review and meta-analysis of pharmacokinetic studies to determine plasma trough concentrations of amlodipine, hydrochlorothiazide, and valsartan. PubMed was searched for pharmacokinetic studies up to September 2020. Eligible studies reported steady-state mean trough concentration and their variance. Pooled trough concentrations were estimated using a three-level random effects meta-analytic model. Moderator analyses were performed to explore sources of heterogeneity. One thousand three hundred eighteen potentially relevant articles were identified of which 45 were eligible for inclusion. The pooled mean trough concentration was 9.2 ng/mL (95% CI, 7.5–10.8) for amlodipine, 41.0 ng/mL (95% CI, 17.4–64.7) for hydrochlorothiazide, and 352.9 ng/mL (95% CI, 243.5–462.3) for valsartan. Substantial heterogeneity was present for all 3 pooled estimates. Moderator analyses identified dosage as a significant moderator for the pooled trough concentration of amlodipine (β₁=0.9; P<0.05), mean age, and mean body weight for the mean trough concentration of hydrochlorothiazide (β₁=2.2, P<0.05, respectively, β₁=−4.0, P<0.05) and no significant moderators for valsartan. Plasma trough concentrations of amlodipine, hydrochlorothiazide, and valsartan, measured with liquid chromatography-tandem mass spectrometry, are highly heterogeneous over the different studies. Use of the pooled trough concentration as a cutoff in the biochemical assessment of adherence can result in inaccurate diagnosis of (non-)adherence, which may seriously harm the patient-physician relationship, and is therefore not recommended.

In vitro study on the effect of ophiopogonin D on the activity of cytochrome P450 enzymes

Ophiopogonin D is a commonly used herb in cardiology and pediatrics for its variuos pharmacological effects. It is necessary to investigate the effect of ophiopogonin D on the activity of cytochrome P450 enzymes (CYP450s) to provide more guidance for the clinical application of ophiopogonin D. Eight isoforms of CYP450s, including CYP1A2, 2A6, 2C8, 2C9, 2C19, 2D6, 2E1, and 3A4 were incubated with 100 μM ophiopogonin D in pooled human liver microsomes. The inhibition model and corresponding parameters were also investigated. Ophiopogonin D exerted a significant inhibitory effect on the activity of CYP3A4, 2C9, and 2E1 in a dose-dependent manner with the IC50 values of 8.08, 12.92, and 22.72 μM, respectively (p < 0.05). The inhibition of CYP3A4 by ophiopogonin D was performed non-competitively and time-dependently with the Ki value of 4.08 μM and the KI/K_inact value of 5.02/0.050 min^-1·μM^-1. Whereas, ophiopogonin D acts as a competitive inhibitor of CYP2E1 and 2C9 with the Ki value of 6.69 and 11.07 μM, respectively. The inhibitory effect of ophiopogonin D on the activity of CYP3A4, 2C9, and 2E1 indicated the potential drug-drug interaction between ophiopogonin D and drugs metabolized by these CYP450s, which needs further in vivo investigation and validation.