Yoshikazu Yamamura

Stereoselective high-performance liquid chromatographic determination of ketamine and its active metabolite, norketamine, in human plasma

A stereoselective high-performance liquid chromatographic method for the determination of the enantiomers of ketamine and its active metabolite, norketamine, in human plasma is described. The compounds were extracted from plasma by liquid-liquid extraction three times in a combination of cyclohexane with 2.5 M NaOH, 1 mM HCl and 1 M carbonate buffer. Stereoselective separation was achieved on a Chiralcel OD column with a mobile phase of n-hexane-2-propanol (98:2, v/v). The detection wavelength was 215 nm. The lower limits of the determination of the method were 5 ng/ml for ketamine and 10 ng/ml for norketamine. The intra- and inter-day coefficients of variation ranged from 2.9 to 9.8% and from 3.4 to 10.7% for all compounds, respectively. The method was sensitive and sufficiently reproducible for stereoselective monitoring of ketamine and norketamine in human plasma during pharmacokinetic studies after the administration of ketamine for analgesia.

Inhibitory Effects of Terpenoids on Multidrug Resistance-Associated Protein 2-and Breast Cancer Resistance Protein-Mediated Transport

The possibility of interactions between natural products/supplements and conventional prescription medicines is one of the most important issues in pharmacotherapeutic safety. Recently, we reported that some terpenoids such as (R)-(+)-citronellal and glycyrrhetic acid, which are present in herbal medicines, can act as inhibitors of P-glycoprotein (MDR1/ABCB1). In the present study, the effects of seven terpenoids on multidrug resistance-associated protein 2 (MRP2/ABCC2) and breast cancer resistance protein (BCRP/ABCG2)-mediated transport were investigated in vitro. Membrane vesicles were prepared from MRP2 cDNA transfected Sf9 cells derived from pupal ovarian tissue of Spodoptera frugiperda, a fall armyworm, and BCRP cDNA transfected LLC-PK1 cells derived from porcine kidney. MRP2- or BCRP-mediated efflux transport was measured as ATP-dependent accumulation of [3H]estradiol 17-β-d-glucuronide (E217βG) into membrane vesicles collected by a rapid filtration technique. The effects of (R)-(+)-citronellal, (S)-(-)-β-citronellol, α-terpinene, terpinolene, (-)-β-pinene, abietic acid, and glycyrrhetic acid on the intravesicular accumulation of [3H]E217βG were examined. Large decreases in the [3H]E217βG accumulation into vesicles from MRP2-overexpressing Sf9 cells were observed in the presence of glycyrrhetic acid and abietic acid, and their IC50 values were about 20 and 51 μM, respectively. [3H]E217βG accumulation into vesicles from BCRP-overexpressing LLC-PK1 cells was suppressed by only glycyrrhetic acid, with an IC50 value of about 39 μM. Other terpenoids used in this study did not alter the ATP-dependent accumulation of [3H]E217βG. These findings suggest that glycyrrhetic acid and abietic acid can potently inhibit MRP2- or BCRP-mediated membrane transport and may interact with their substrates in pharmacokinetic processes.

The pharmacokinetics of glycyrrhizin and its restorative effect on hepatic function in patients with chronic hepatitis and in chronically carbon-tetrachloride-intoxicated rats

The relationships between the pharmacokinetic behaviour of glycyrrhizin and its restorative effect for hepatic function were investigated in patients with chronic hepatitis and in rats chronically treated with carbon tetrachloride (CCl4‐treated rats). In patients, the restorative effects in plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities were 62·2±7·4 and 64·4±7·5%, respectively, after daily 80 mg intravenous (i.v.) doses of glycyrrhizin for 2 weeks, and 63·1±19·1 and 68·7±15·2% after 120 mg doses. The present work suggests that the threshold plasma glycyrrhizin concentration for sufficient effect is near 5 μg mL−1. In rats, the total body clearance (Cltot) for glycyrrhizin in the CCl4‐treated rats after i.v. administration of glycyrrhizin (5 mg kg−1 dose) was three‐tenths of that of the control, and the t1/2 for glycyrrhizin was 3·4‐fold longer than that of the control. A good correlation was observed between Cltot and AST (r=−0·838) or ALT (r=−0·873) activity in both rats. When glycyrrhizin was administered intraperitoneally (i.p.) three times a week for 2 weeks, both the AST and ALT activities in the CCl4‐treated rats showed a greater improvement than for a 10 mg kg−1 dose. Furthermore, the finding on the threshold plasma concentration in patients as above was also supported from the results of the experiments in rats.

Selective high-performance liquid chromatographic method for the determination of glycyrrhizin and glycyrrhetic acid-3-O-glucuronide in biological fluids: application of ion-pair extraction and fluorescence labelling agent.

A selective high-performance liquid chromatographic method has been developed for the simultaneous determination of glycyrrhizin and glycyrrhetic acid-3-O-glucuronide in biological fluids of the rat. The procedure is based on the ion-pair formation using tetra-n-amylammonium bromide, extraction with ethyl acetate-n-heptane from the salt-saturated aqueous phase, labelling with 4-bromomethyl-7-methoxycoumarin, followed by chromatographic separation with fluorescence detection. Glycyrrhizin in plasma, bile and urine could be precisely determined in concentrations as low as 1, 1 and 2.5 micrograms/ml, respectively, in a 0.1-ml sample. The equivalent values for the glucuronide were 1, 2.5 and 2.5 micrograms/ml, respectively. The method is applicable in pharmacokinetic studies of glycyrrhizin in small animals.

エトポシド(VP-16)注射液の持続注入時に発生したポリウレタン製カテーテル亀裂の要因に関する検討

We studied the cause of cracking of a clinically used polyurethane (PU) catheter during the constant infusion of etoposide (VP-16) injection (Lastet), administered without dilution to patients as a part of combination high-dose chemotherapy. After VP-16 injection was infused into the PU catheter at a constant infusion rate (30 ml/h) for 24 h, a decrease in the elasticity (36% of untreated) and on increase in the length of the catheter (3.7%) were observed. These changes were significantly higher than those treated with the control saline. The similar changes of the PU catheter were observed after treatment with a basal solution containing polyethylene glycol 400 (PEG 400), polysorbate 80 and ethanol, which is the vehicle of the VP-16 injection, and with ethanol alone. Moreover, obvious degeneration of the internal wall (occurrence of spots like melting) and cutting face (micro-cracking) of the catheter was observed with an electron microscope after treatment with the vehicle. On the other hand, the elasticity or extension of the PU catheter were not changed after treatment with saline or PEG 400. From these findings, it was suggested that the degeneration and subsequent cracking of the PU catheter during the infusion of VP-16 injection was caused by ethanol contained in its injection solution. No cracking or morphological changes of polyvinyl chloride (PVC) and silicone catheters were found after treatment with the vehicle solution. However, since it has been reported in previous reports that di(2-ethylhexyl)phthalate was leached from PVC bags, the high dose chemotherapy with the dilution-free VP-16 injection should be achieved safely and effectively using a silicon catheter, rather than the PU catheter.

Quantitative determination of propranolol in plasma and plasma water from normal subjects and patients with angina pectoris by high-performance liquid chromatography

A precise and sensitive high-performance liquid chromatographic method using a column packed with porous polystyrene gel is described for the determination of propranolol in plasma and plasma water from normal subjects and patients with angina pectoris. Propranolol in the samples was extracted with an n-heptane-isoamylalcohol (98.5:1.5) mixture after addition of penbutolol used as an internal standard. The extracts were chromatographed and detected with a spectrofluorophotometer. The quantitative limit of propranolol was 1 ng using 1 ml of plasma or 0.5 ml of plasma water. The present method should be useful for monitoring propranolol concentrations in plasma and plasma water during drug therapy and for pharmacokinetic study of propranolol.

Improvement of the Convenience of White Petrolatum

White petrolatum is frequently used as an oleaginous base, but has a drawback of poor usability. In this trial, white petrolatum was prepared at a lower melting point to improve its usability. Characteristic pharmaceutical values such as melting point, yield, and consistency were compared between a conventional product and ophthalmic white petrolatum. Usability was compared by administering a survey questionnaire and evaluating the comparable moisturizing effect by conductivity in humans. The melting point and yield value of the improved product were significantly lower compared with other white petrolatum products. In the survey, the improved product was rated excellent in five criteria. On a scale of 1 to 5, the average values for the five criteria for the improved product were 4.7, while the conventional product and ophthalmic white petrolatum were rated 3.0 and 3.5, respectively. No difference in moisturizing effect was observed among all petrolatums after application, from day 1 to day 14. In conclusion, the improved white petrolatum demonstrated better usability, and the moisturizing effect was equivalent to conventional product, suggesting that the use of this improved product may lead to improved adherence.

Running-state Analysis of the Outpatient Consultation for Drug Compliance and Development of a Management System of the Consultation Records Based on an In-hospital LAN.

Since we started both active and passive consultation regarding drug compliance for outpatients at the department of pharmacy, University of Tokyo Hospital in 1991, the records of such consultation have been carefully kept on ‘drug consultation sheets’. In the present study, we analyzed the consultation records from April to September in 1998. The case number of consultation during this period was 627; among them, active instructions were given to 409 cases (65%) while passive instructions were given to the others. The analysis showed that 28 cases (14patients) out of 627 cases experienced our consultation more than once; 13 (93%) of such patients were advised by different pharmacists and 10 (71%) were advised regarding the same drug, thus suggesting the need for a quick retrieval of past records. As a result, we designed a software system to integrate an electronic database for consultation records, including the contents of consultations, a list of the prescribed drugs and any OTC drugs which have been taken, the patients characteristics, and a history of using a medication diary (so-called ‘Okusuri Techo’). We set up a local area network (LAN) using the database inside the hospital so that all accumulated information could be easily retrieved from any hospital terminal. The intranet-based management system of outpatient consultation records has now enabled a high consistency and efficiency in consultations by different pharmacists while also allowing for a quick compilation of all medical records.