Calycosin Influences the Metabolism of Five Probe Drugs in Rats.

BACKGROUND: Calycosin (CAL), a type of O-methylated isoflavone extracted from the herb Astralagusmembranaceus (AM), is a bioactive chemical with antioxidative, antiphlogistic and antineoplastic activities commonly used in traditional alternative Chinese medicine. AM has been shown to confer health benefits as an adjuvant in the treatment of a variety of diseases. AIM: The main objective of this study was to determine whether CAL influences the cytochrome P450 (CYP450) system involved in drug metabolism. METHODS: Midazolam, tolbutamide, omeprazole, metoprolol and phenacetin were selected as probe drugs. Rats were randomly divided into three groups, specifically, 5% Carboxymethyl cellulose (CMC) for 8 days (Control), 5% CMC for 7 days + CAL for 1 day (single CAL) and CAL for 8 days (conc CAL), and metabolism of the five probe drugs evaluated using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). RESULTS: No significant differences were observed for omeprazole and midazolam, compared to the control group. T max and t1/2 values of only one probe drug, phenacetin, in the conc CAL group were significantly different from those of the control group (T max h: 0.50±0.00 vs 0.23±0.15; control vs conc CAL). C max of tolbutamide was decreased about two-fold in the conc CAL treatment group (conc vs control: 219.48 vs 429.56, P<0.001). CONCLUSION: Calycosin inhibits the catalytic activities of CYP1A2, CYP2D6 and CYP2C9. Accordingly, we recommend caution, particularly when combining CAL as a modality therapy with drugs metabolized by CYP1A2, CYP2D6 and CYP2C9, to reduce the potential risks of drug accumulation or ineffective treatment.

Identification of the active components in Shenmai injection that differentially affect Cyp3a4-mediated 1'-hydroxylation and 4-hydroxylation of midazolam.

Shenmai injection (SMI) is a popular herbal preparation that is widely used for the treatment of atherosclerotic coronary heart disease and viral myocarditis. In our previous study, SMI was shown to differentially affect CYP3A4-mediated 1'-hydroxylation and 4-hydroxylation of midazolam (MDZ). The present study was conducted to identify the active components in SMI responsible for the differential effects on MDZ metabolism, using in vitro incubation systems (rat and human liver microsomes and a recombinant CYP3A4 system) to measure 1'-hydroxylation and 4-hydroxylation of MDZ. First, different fractions of SMI were obtained by gradient elution on an solid phase extraction system and individually tested for their effects on MDZ metabolism. The results demonstrated that lipid-soluble constituents were likely to be the predominant active components of SMI. Second, the possible active components were gradually separated on an high-performance liquid chromatography system under different conditions and individually tested in vitro for their effects on MDZ metabolism. Third, the active component obtained in the above experiment was collected and subjected to structural analysis, and identified as panaxytriol (PXT). Finally, it was validated that PXT had significant differential effects on 1'-hydroxylation and 4-hydroxylation of MDZ in various in vitro systems that were similar to those of SMI. We conclude that PXT is the constituent of SMI responsible for the differential effects on CYP3A4-mediated 1'-hydroxylation and 4-hydroxylation of MDZ.

The impact of multilumen infusion devices on the occurrence of known physical drug incompatibility: a controlled in vitro study.

BACKGROUND: Drug incompatibility is a problem, especially when managing patients in intensive care units. We designed the present study to assess the impact of multilumen infusion access devices on the occurrence of known physical drug incompatibility through a controlled in vitro study. METHODS: Three infusion devices connected to a single-lumen catheter were studied: a standard set with 2-port manifold and 1-m extension set and 2 multilumen infusion access devices: a 3-lumen extension set and a 9-lumen extension set (Edelvaiss-Multiline™; Doran International, Toussieu, France). For the 9-lumen extension set, 3 infusion access combinations were studied. Furosemide, midazolam, and saline were infused simultaneously through 3 infusion devices. Three concentrations of furosemide were tested. The infusion rate of saline (carrier) was initially set at 100 mL/h and stepwise decreased by 10 mL/h until precipitate formation. Physical incompatibility was assessed by 2 tests: visual inspection and the subvisible particle count test according to the European Pharmacopeia. The lowest saline infusion rate to prevent visible precipitate and attain an acceptable particle count (i.e., to pass "the 2 tests") was reported for each infusion set. RESULTS: The standard set revealed visible precipitate even at the highest saline flow rate (100 mL/h). The 3-lumen device prevented drug precipitation using the 2 lowest furosemide concentrations with a saline infusion rate that decreased with furosemide concentration. The 9-lumen infusion access device prevented drug precipitation whatever the furosemide concentration for 2 access combinations using saline infusion rates of between 20 and 60 mL/h but not for a third access combination, despite saline infusion rates equal to 100 mL/h. CONCLUSIONS: Infusion device characteristics appear to have an impact on the physical compatibility of the 2 drugs. Under specified conditions, the 9-lumen infusion access device prevents physical furosemide-midazolam incompatibility.

Development and characterization of mucoadhesive in situ nasal gel of midazolam prepared with Ficus carica mucilage.

The objective of the present study was to prepare mucoadhesive in situ nasal gels with mucilage isolated from fig fruits (Ficus carica, family: Moraceae) containing midazolam hydrochloride. Nasal gels of midazolam were prepared using three different concentrations (0.5%, 1.0% and 1.5% w/v) of F. carica mucilage (FCM) and synthetic polymers (hydroxypropylmethyl cellulose and Carbopol 934). Evaluation of FCM showed that it was as safe as the synthetic polymers for nasal administration. In situ gels were prepared with mixture Pluronic F127 and mucoadhesive agents. Evaluation of the prepared gels was carried out, including determination of viscosity, texture profile analysis and mucoadhesive strength. In vitro drug permeation study was conducted with the gels prepared with and without permeation enhancer (0.5% w/v sodium taurocholate) using excised goat nasal mucosa. In vitro permeation profiles were evaluated, and histological study of nasal mucosae before and after permeation study was also conducted to determine histological change, if any. In vivo experiments conducted in rabbits further confirmed that in situ nasal gels provided better bioavailability of midazolam than the gels prepared from synthetic mucoadhesive polymers. It was observed that the nasal gel containing 0.5% FCM and 0.5% sodium taurocholate exhibited appropriate rheological, mechanical and mucoadhesive properties and showed better drug release profiles. Moreover, this formulation produced no damage to the nasal mucosa that was used for the permeation study, and absolute bioavailability was also higher compared to gels prepared from synthetic polymers.

In vitro investigation on the impact of the surface-active excipients Cremophor EL, Tween 80 and Solutol HS 15 on the metabolism of midazolam.

The impact of the surface-active formulation ingredients Cremophor EL, Tween 80 and Solutol HS 15 on the intrinsic clearance (Clint) of midazolam (MDZ) was investigated in rat hepatocytes and microsomes. In rat hepatocytes with 0.003%, 0.03% and 0.3% (w/v) Solutol HS 15 already present in the incubation medium, the Clint was significantly reduced in a dose-dependent manner by about 25%, 30% and 50%, respectively. In the presence of Cremophor EL and Tween 80 a significant reduction in Clint by about 30% and 25%, respectively, was observed at 0.03% surfactant concentration. At 0.3% of Cremophor EL and Tween 80, Clint was reduced by about 50% and 20%, respectively. A reduction in Clint was also observed in experiments with rat liver microsomes. At surfactant concentrations up to 0.03%, cytotoxicity assays (lactate dehydrogenase release, adenosine triphosphate content) as well as light microscope investigations did not reveal any cytotoxic impact of the surfactants on the hepatocyte monolayer. A potential interaction of the surfactants with biological membranes was determined using phosphatidylcholine-cholesterol liposomes loaded with self-quenching concentrations of carboxyfluorescein. No marked release of carboxyfluorescein from the liposomes (that would be an indication for a surfactant-dependent disruption of membrane integrity) was observed up to concentrations of 0.03% of the different surfactants. It is concluded that cytochrome P450 3A mediated metabolism of MDZ seems to be prevented by all surfactants at concentrations above 0.03%. In our experiments the surfactants did not show toxic effects at concentrations that resulted in a decreased Clint of MDZ. Thus, a direct inhibition of the metabolizing enzymes, a molecular interaction with the microsomes as well as an alteration of membrane properties that did not yet result in a release of LDH have to be taken into consideration as reasons for the observed changes in the metabolism of MDZ.

Stability of midazolam prepared for oral administration.

Midazolam is used frequently as an oral premedication in children. To make it more palatable, it is often mixed in various syrups and solutions. No previous studies have documented the stability of midazolam when mixed in these solutions. Using high-pressure liquid chromatography, we assayed midazolam concentrations over time when mixed at two different concentrations (2.5 mg/mL and 3.0 mg/mL) in a sucrose-based syrup (Simple Syrup, NF). Each assay was done in triplicate on three different days (days 1, 14, and 38). Solution A concentrations (2.5 mg/mL) were 2.28 mg/mL on day 1, mg/mL) were 2.82 mg/mL on day 1, 2.91 mg/mL on day 14, and 2.24 mg/mL on day 38. Our results confirm the stability of midazolam for up to 14 days when mixed for oral administration.