Abstract
Purpose: To investigate the pharmacokinetic mechanism of interaction between magnolol and piperine when co-administered to rats. Methods: The rats were divided into five groups as follows: magnolol group (625 mg/kg); low dose of piperine group (20 mg/kg); high dose of piperine group (40 mg/kg); low dose of piperine + magnolol group; or high dose of piperine + magnolol group. Plasma samples were collected at regular time intervals after administration of a single dose of magnolol (625 mg/kg, p.o.) alone or piperine (20 or 40 mg/kg, p.o.) in the presence or absence of magnolol (625 mg/kg, p.o.). The concentrations of magnolol and piperine in plasma were measured by a validated high performance liquid chromatography (HPLC) method. Results: Compared with control, the groups given magnolol alone, concomitant administration of piperine and magnolol resulted in significant decrease (p 0.05) alter the pharmacokinetic parameters of piperine. However, at high dose (40 mg/kg) of piperine, C max of piperine significantly decreased from 4.30 ± 1.47 to 2.50 ± 0.78 μg/mL (p < 0.05). Conclusion: Co-administration of magnolol and piperine decreases plasma concentration of either drug in rats, suggesting that concurrent use of magnolol with piperine or piperine-containing diets would require close monitoring for potential interactions. Keywords: Magnolol, Piperine, Pharmacokinetic interaction, Co administration
Highlights
Magnolol a substrate for P-glycoprotein (P-gp), shown in Figure 1a, is one of the major compounds contained in the bark of Magnolia officinalis, which has been widely prescribed for the treatment of gastrointestinal diseases [1]
The calibration curve from magnolol was found to be linear over the concentration range of 0.8 to 20 μg/mL in rat plasma with the linear regression equation Y=0.0775X-0.0295 (R2 = 0.9998)
The intra- and inter-day precision of magnolol was < 10 %, and accuracy ranged from -3.3 to 8.9 %
Summary
Magnolol a substrate for P-glycoprotein (P-gp), shown in Figure 1a, is one of the major compounds contained in the bark of Magnolia officinalis, which has been widely prescribed for the treatment of gastrointestinal diseases [1]. The oral bioavailability of magnolol, is reported to be only 5 % due to extensive first-pass metabolism and low absorption [5]. Efflux transporters such as P-gp are critical functional proteins in drug metabolism and transport, and have been shown to limit oral drug absorption and tissue distribution [6]. Piperine (1-peperoyl peperidine, Figure 1b), a major active ingredient of black pepper (Piper nigrum Linn.) and long pepper (Piper longum Linn.), has been shown to have fundamental effects on P-gp and many enzyme systems, leading to biotransformative effects including detoxification and enhancement of the absorption and bioavailability of herbal and conventional drugs. Piperine has been found to increase the plasma concentrations of various structurally and therapeutically diverse drugs, such as theophylline, phenytoin, rifampin, and propranolol [7], possibly due to the inhibition of metabolic pathways and /or P-gp-mediated drug efflux
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