三原 潔

<title>Abstract</title><sec> <title>Background</title> Anticholinergic burden potentially increases the risk of fracture. Although there are various anticholinergic burden scales, little is known about the inter-scale compatibility regarding the relationship of anticholinergic burden with fracture risk. We performed meta-analysis to examine the association of fracture risk with anticholinergic burden measured using various scales. </sec><sec> <title>Methods</title> Primary literature was retrieved from PubMed (1966 to March, 2021), the Cochrane Library (1974 to March, 2021), Scopus (1970 to March, 2021), and Ichushi-web (1983 to March, 2021). Cohort and case-control studies that evaluated the association between any fracture and anticholinergic drugs were included. Additionally, we included studies in which patients were administered anticholinergic drugs included on the anticholinergic risk scale (ARS), anticholinergic cognitive burden (ACB), anticholinergic drug scale, or drug burden index-anticholinergic component. Random effects models were used to calculate pooled relative risk (RR) and 95% confidence interval (CI) due to heterogeneity among the studies. Publication bias was examined by funnel plots and the Begg’s test. </sec><sec> <title>Results</title> A total of 49 datasets from 10 studies were included in the meta-analysis. Six of the 10 studies included only patients aged over 65 years, who accounted for 93% of the total study population (453,186/487,247). Meta-analysis indicated a positive relationship between use of anticholinergic drugs and fracture risk, regardless of the anticholinergic burden scale used. However, the relationship between anticholinergic burden and fracture risk varied depending on the scale used. Fracture risk increased linearly with increasing anticholinergic burden measured using ARS. ARS 1 point was associated with 28% increase in fracture risk, ARS 1–2 point(s) with 39%, ARS 2 points with 54%, ARS 3 points with 66%, and ARS ≥ 4 points with 77%. On the other hand, ACB 1 point and ACB 2 points were associated with similar fracture risk (pooled RR [95% CI]: overall; 1.28 [1.18–1.39], 1 point; 1.12 [1.06–1.18], 2 points; 1.15 [1.08–1.23]). </sec><sec> <title>Conclusions</title> This result suggests that the relationship between anticholinergic drug burden and fracture risk may differ depending on the anticholinergic burden scale used. </sec>

BACKGROUND: Population differences in warfarin dosing requirement have been reported; however, unlike the pharmacokinetics (PK) of warfarin, the quantitative influences of pharmacodynamic (PD) factors on the anticoagulation response to warfarin in different ethnic populations are totally unknown. METHODS: Using population PK/PD analysis, we attempted to identify predictors of S-warfarin clearance [CL(S)] and half maximal effective concentration (EC50) to quantify racial differences in both PK and PD parameters, and to assess the contribution of these parameters to the international normalized ratio (INR) and over-anticoagulation response (INR ≥ 4) in a cohort of 309 White, Asian and African American patients. RESULTS: Similar to our previous findings, the median CL(S) was 30% lower in African American patients than Asian and White patients (169 vs. 243 and 234 mL/h, p < 0.01). EC50 showed a greater racial difference than CL(S) [1.03, 1.70 and 2.76 μg/mL for Asian, White and African American patients, respectively, p < 0.01). Significant predictors of INR included demographic/clinical (age, body weight, creatinine clearance and sex) and genotypic (CYP2C9*3,*8 and VKORC1 -1639G>A) factors, as well as African American ethnicity. In all three racial groups, genetic predictors of INR appeared to have greater influence than demographic/clinical predictors. Both CL(S) and EC50 contributed to the over-anticoagulation response to warfarin. Patients having VKORC1 -1639 G>A and/or factors associated with reduced CYP2C9 activity were more likely to have an INR ≥ 4. CONCLUSIONS: Although there were contrasting racial differences in CL(S) and EC50 that impacted on the INR, the racial difference in EC50 was greater than that for CL(S), thus explaining the higher warfarin requirement for African American patients.

学生にとって充実した質の高い実習を行うためには、学生が実習を通じて如何に成長できたと感じたか、すなわち実習をどの程度有意義と感じたかが重要と考えられる。今回、有意義度に影響する因子を明らかにするため、2012〜2017年度に実務実習を受けた学生830名に対して実習終了直後に行ったアンケートの回答を分析した。結果、有意義度に大きな影響を与える因子は、実習中の患者とのコミュニケーションの頻度と、指導薬剤師の実習生への対応(準備・熱心さ・質問のしやすさ)であると考えられた。

リハビリテーション病棟における高齢入院患者の薬剤数に影響を与える因子について検討した。回復期リハビリテーション病棟へ入院した124例(男性57名、女性67名、81±8歳)を調査対象とした。入院時および退院時の処方内容を基に、薬効群別に服用人数を調査した。退院時内服薬数の中央値は6剤で、退院時に多剤併用(7剤以上の内服薬処方)患者は51例であった。入院時から退院時迄の内服薬数の変化について薬効群別に検討すると、解熱鎮痛消炎剤が服用者数および合計薬剤数ともに有意に減少した。消化性潰瘍剤および高脂血症用剤、痛風治療剤、抗パーキンソン剤を含むその他の薬剤は、服用者数に有意差はなかったものの合剤薬剤数が退院時迄に有意に減少した。血圧降下剤はアンジオテンシン変換酵素阻害薬あるいはアンジオテンシンII受容体拮抗薬、およびCa拮抗薬の退院時処方率が各約40%程度と高かった。重回帰分析で有意となった説明因子は入院時内服薬数、心臓疾患の有無、高血圧症の有無の3因子であった。

Pregabalin, a useful drug for neuropathic pain, has a high incidence of dizziness and somnolence as side effects. In the present study, the incidence of both side effects and the risk factors were retrospectively investigated in hospitalized patients who were administered pregabalin after their admission. In 65 patients (median 68 years old), 34 cancer patients and 18 opioid users were included. Items studied were cancer/non-cancer, opioid user/non-user, fall/nonfall, age, sex, weight, daily dose of opioids, the number of the drugs that may cause dizziness and somnolence, daily dose of pregabalin, and the ratio of creatinine clearance to daily dose of pregabalin. Fourteen (21.5%) and 21 (23.3%) patients developed dizziness and somnolence, respectively, and 4 (6.1%) patients developed fall. In the case of opioid combination, 7 (38.9%) and 10 (55.6%) patients developed dizziness and somnolence, respectively. A logistic-regression analysis showed that opioid use is a significant augmenting risk factor for dizziness (P = 0.026) and somnolence (P = 0.016) of pregabalin. The ratios of daily dose of pregabalin to creatinine clearance did not show any relation to the incidence of dizziness and somnolence; both side effects were observed in some patients whose renal functions were normal. It is suggested that attention is necessary to the incidence of dizziness and somnolence regardless of renal function, and that particular attention is required when opioids, which have similar side effects, are combined with pregabalin.

To clarify pharmacokinetic-pharmacodynamic (PK-PD) factors associated with the over-anticoagulation response in Asians during warfarin induction therapy, population PK-PD analyses were conducted in an attempt to predict the time-courses of the plasma S-warfarin concentration, Cp(S), and coagulation and anti-coagulation (INR) responses. In 99 Chinese patients we analyzed the relationships between dose and Cp(S) to estimate the clearance of S-warfarin, CL(S), and that between Cp(S) and the normal prothrombin concentration (NPT) as a coagulation marker for estimation of IC50. We also analyzed the non-linear relationship between NPT inhibition and the increase in INR to derive the non-linear index lambda. Population analyses accurately predicted the time-courses of Cp(S), NPT and INR. Multivariate analysis showed that CYP2C9*3 mutation and body surface area were predictors of CL(S), that VKORC1 and CYP4F2 polymorphisms were predictors of IC50, and that baseline NPT was a predictor of lambda. CL(S) and lambda were significantly lower in patients with INR &gt;= 4 than in those with INR, 4 (190 mL/h vs 265 mL/h, P&lt;0.01 and 3.2 vs 3.7, P&lt;0.01, respectively). Finally, logistic regression analysis revealed that CL(S), ALT and hypertension contributed significantly to INR &gt;= 4. All these results indicate that factors associated with the reduced metabolic activity of warfarin represented by CL(S), might be critical determinants of the over-anticoagulation response during warfarin initiation in Asians.

Establishment of in vitro in vivo correlation (IVIVC) accelerates optimization of desirable drug formulations and/or modification of the manufacturing processes in the scale-up and post-approval periods. This article presents a method of finding the optimal conversion function for establishing Level A point-to-point IVIVC, based on a computer-based evolutionary search technique. Gene expression programming (GEP) is a technique for optimizing a mathematical expression tree with the help of a genetic algorithm. A parameter optimization routine, which minimizes the number of parameters in the mathematical expression trees and estimates the best-fit parameter values, was implemented in the GEP algorithm. Feasibility of the computer program was investigated using the in vitro and in vivo data for sustained release diltiazem formulations. It provided a mathematical equation that, from their in vitro dissolution profiles, successfully predicts the plasma concentration profiles of three different formulations of diltiazem following oral administration. Because the present approach does not use intravenous injection data like conventional IVIVC analyses, it is widely applicable to the evaluation of various oral formulations.

Background and Objective Genetic polymorphisms of cytochrome P450 (CYP) 2C9 (CYP2C9) and vitamin K epoxide reductase complex subunit 1 (VKORC1) and patient demographic characteristics are responsible for inter-individual differences in warfarin maintenance dosage requirements. At present, however, the factors associated with over-anticoagulation responses, especially before achieving the maintenance phase, have not been completely clarified. In this study, we investigated the effects of baseline coagulation activity assessed in terms of the level of fully carboxylated plasma normal prothrombin (NPT) on international normalized ratio (INR) control during the induction phase of warfarin therapy. Our objectives were to (1) identify factors associated with inter-patient variability in baseline NPT (NPT0); (2) estimate the therapeutic NPT (NPTtx) levels that can achieve an INR of 2-3; and (3) investigate the influence of NPT0 on the INR response to warfarin by employing modelling and simulation techniques. Methods We measured NPT before (NPT0) and during the introduction of warfarin therapy for up to 3 months and analysed functional single nucleotide polymorphisms (SNPs) of VKORC1 and CYP4F2 in 179 Chinese patients. The patients were classified into tertile groups according to NPT0 values (i.e. high, intermediate and low groups), and in each group the NPTtx achieving therapeutic INR, the absolute reduction of NPT from NPT0 to NPTtx, and the percentage inhibition of NPT0 [{(NPT0 - NPTtx)/NPT0} x 100] were obtained. The nonlinear relationship between NPT and INR was modelled on the basis of the INR value before warfarin treatment (INR0) added by the nonlinear increase in INR after warfarin initiation, which was predicted using the percentage inhibition of NPT0 and a nonlinear coefficient (lambda). The population parameter lambda and its inter-individual variability and intra-individual variability in INR in the NPT-INR model were estimated by nonlinear mixed-effect modelling software NONMEM (R). Results Multivariate analysis identified age and liver disease as covariates of NPT0, but none of the SNPs had a significant influence. Although the mean absolute NPT reduction necessary to achieve NPTtx was dependent on NPT0 (i.e. the higher the NPT0, the larger the reduction in NPT), the percentage inhibition was within the narrow range of 67-72 % of NPT0, irrespective of NPT0. However, a significantly higher percentage inhibition (80 % on average) was observed in patients with INR values exceeding 4.0. As the nonlinear coefficient lambda in the developed model was dependent on NPT0 (i.e. the higher the NPT0, the larger the nonlinear lambda value), the simulated nonlinear NPT-INR curves were superimposable in the three respective NPT0 groups, and the only difference was the starting median NPT0 level. As a result, a steeper increase in the slope of the nonlinear NPT-INR curve might be expected in patients with a lower NPT0 after initiation of warfarin. Conclusions The present study suggests that INR may be prolonged by warfarin nonlinearly as a function of the percentage inhibition of NPT0. Furthermore, these results indicate that NPT0 may contribute to inter-individual variability in the INR response, and that patients with low NPT0 may have the potential to show a sharp increase in INR during initiation therapy with warfarin.

4年制薬学教育における病院実習の問題点を解析し、6年制の実務実習に向けての改善策を提案した。

Carvedilol is a beta-adrenoceptor antagonist used for treating chronic heart failure (CHF). Two clinical studies were conducted to evaluate the population pharmacokinetics and pharmacodynamics of R- and S-carvedilol, and associated covariates, in patients with CHF. Fifty-eight patients (male=45, female=13) with New York Heart Association class I TV CHF were enrolled in two clinical studies. R- and S-carvedilol concentrations were measured using HPLC at steady-state after oral administration of carvedilol at 1.25-20 mg o.d. or b.i.d. The data from both studies were used to estimate the population pharmacokinetic parameters and covariates using the nonlinear mixed effects model program. For 40 patients evaluated in one clinical study, the cytochrome P450 (CYP)2D6 *1, *10, and *5 genotypes were determined using allele-specific primer PCR, and individual patients' oral clearance (CL/F) of both enantiomers were estimated by the empirical Bayes method. A one-compartment model with a first-order absorption rate was established, in which body weight and alpha(1)-acid glycoprotein were significant covariates. Individual CL/F values for carvedilol were significantly lower in Japanese CHF patients with the CVP2D6 *1/*5, *5/*10 and *10/*10 genotypes. Estimation of the population pharmacokinetic parameters and their covariates for each enantiomer in Japanese patients with CHF showed that the CL/F values for Rand S-carvedilol were dependent on body weight, alpha(1)-acid glycoprotein, and CVP2D6 genotype. Prediction of exposure to free plasma carvedilol is important for dosage adjustment of beta-blocker therapy in patients with CHF.

Diabetes mellitus is a well known and important risk factor for cardiovascular diseases, including heart failure. A new model of Type 2 diabetes, Tsumura Suzuki Obese Diabetes (TSOD) mice, was introduced recently into the research field of diabetes. The cardiac functions of TSOD mice were studied in comparison with Tsumura Suzuki Non Obesity (TSNO, non-diabetic control) mice, for the first time. In vivo cardiovascular functions were measured by echocardiography and cardiac catheterization at 7, 12 and 18 months old. TSOD mice had no deterioration of cardiac function despite the long-term persistence of severe obesity, hyperglycemia, hyperinsulinemia and hyperlipidemia, including high density lipoprotein (HDL)-cholesterol. No histopathological abnormalities were observed in the heart of TSOD mice, while several histological abnormalities were observed in the pancreas and kidney of TSOD mice. To investigate vascular endothelium function at 7 months old, intravenous injection of acetylcholine (ACh; 1, 3, 10 mu g/kg)- and N-G-nitro-L-arginine methyl ester (L-NAME; 50 mg/kg)-induced mean blood pressure (BP) changes were used. ACh decreased whereas L-NAME increased BP, and no significant differences in BP changes were observed between TSOD and TSNO mice. Moreover, ACh-induced relaxation of the thoracic aortae isolated from TSOD and TSNO mice with intact endothelium were not significantly different. These findings suggest that vascular endothelial cells in TSOD mice are not impaired. It was clearly demonstrated that despite obvious diabetes, cardiac functions of TSOD mice were not impaired even at 18 months old.

Dissolution testing is useful for controlling the quality of an oral generic equivalent (GE) drug and rejecting a bioinequivalent GE. However, several sources of variability in dissolution tests can affect evaluations of drug quality. Recently, we reported that shifting the paddle shaft off-center significantly changed the dissolution rate of sodium diclofenac tablets, with the result that some GE tablets did not meet the criteria for equivalence. The aim of this study was to confirm the effect of paddle position and to investigate the effect of inclining the dissolution apparatus on the dissolution rates, quality assessment, and equivalence assessment of rapid-release carbamazepine tablets using a brand product (BR) and three GE products. Dissolution tests were carried out on the basis of the Japanese Pharmacopoeia (JP) 15 and Japanese Orange Book paddle methods. The paddle was shifted 5 mm from the center of the vessel, and the dissolution apparatus was inclined backward approximately 4 degrees from the horizontal position. The percentage of drug that dissolved was then calculated. Shifting the paddle significantly increased the dissolution rate for all tablets, whereas inclining the apparatus reduced the dissolution rate for some tablets. All carbamazepine tablets passed the quality evaluation, and all GE products were judged equivalent to the BR product when the paddle was positioned centrally and the apparatus was horizontal. However, the BR product did not meet the criteria of the quality evaluation, and one GE product was judged not equivalent to the BR product in the 5-mm-off-center experiment, suggesting that the position of the paddle affects the quality and equivalence assessment of the rapid-release carbamazepine tablets. In conclusion, offsetting the paddle position from the center could affect the equivalence, as well as the quality assessment, of GEs by enhancing the dissolution rate. Inclining the apparatus reduced the dissolution rate but did not affect the equivalence assessment of GEs.

Dissolution testing is useful for controlling the quality of oral products and rejecting bioinequivalent products. However, several sources of variability in dissolution tests can affect evaluations of quality. The purpose of this study was to investigate the effects of paddle-shaft position on the dissolution rates of a brand-name (BR) and four generic-equivalent (GE), rapid-release tablets of sodium diclofenac. The paddle was shifted 5 mm from the center of the vessel, and the dissolution profiles were compared with that obtained at the central position. Although the GEs had a wide range of variability and significantly different dissolution profiles, they were estimated to be equivalent to the BR when the paddle was set at the center of the vessel. The 5-mm-shifted position significantly increased the dissolution rates Of all products with the result that some GEs did not meet the criteria for equivalence. In conclusion, paddle position is potentially a cause of error in GE equivalence assessments. The paddle should be accurately positioned at the center of the vessel in dissolution tests for the equivalence assessment of GEs.

Verapamil (VP) is used as a racemate but shows stereoselective pharmacokinetics and pharmacodynamics. It undergoes extensive first-pass metabolism. Stereoselective first-pass metabolism in the intestine and liver was investigated in vivo and in vitro to determine its impact on the disposition of VP and its main metabolite, norverapamil (NVP). VP racemate was administered to rats i.v., p.o., and via the portal vein. The formation rates of the main metabolites of the VP enantiomers were estimated in an in vitro intestinal microsomal study. The hepatic bioavailability of VP showed saturable metabolism, and the hepatic bioavailability of R-VP was higher than that of S-VP. Conversely, the intestinal bioavailability of R-VP was lower than that of S-VP, resulting in a higher systemic bioavailability of S-VP. The pharmacokinetics of the NVP enantiomers was similar. These results suggest that the stereoselectivity of the total bioavailability of VP is determined by first-pass metabolism in the small intestine and liver, and that the NVP enantiomers observed in the systemic circulation after p.o. administration of VP racemate originate mainly from the liver in rats.

A highly sensitive HPLC method for enantioselective determination of carvedilol inhuman whole blood and plasma was developed. Carvedilol and S-carazolol as an internal standard extracted from whole blood or plasma were separated using an enantioselective separation column (Chiralpak AD column; 2.0 circle divide x 250 mm) without any chiral derivatizations. The mobile phase was hexane:isopropanol:diethylamine (78:22:1, v/v). The excitation and emission wavelengths were set at 284 and 343 nm, respectively. The limits of quantification for the S(-)- and R(+)-carvedilol enantiomers in plasma and blood were both 0.5 ng/ml. Intra- and inter-day variations were less than 5.9%. As an application of the assay, concentrations of carvedilol enantiomer in plasma and blood samples from 15 patients treated with carvedilol for congestive heart failure were determined. (c) 2006 Elsevier B.V. All rights reserved.

Population pharmacokinetics (PK) of a sodium channel-blocking antiarrhythmic, pilsicainide, was studied using the nonlinear mixed-effects modeling technique in 91 patients with cardiac arrhythmias (80 suspected Brugada syndrome [BrS] and 11 with atria] fibrillation) who received an intravenous infusion of 10 mg of the drug. Population pharmacodynamic (PD) analysis was also performed using an effect compartment model. PD responses were assessed by changes in electrocardiogram (ECG) pattern (BrS-like elevation of ST segment) and conduction parameters. The final PK model showed that gender (values were 50% lower in women than in men) and creatinine clearance were significant (P &lt;.01) covariates of weight-normalized systemic clearance of pilsicainide. Patients who showed a BrS-like ECG pattern after the drug administration also showed a significantly (P &lt;.01) greater prolongation in His-Purkinje conduction compared to the remaining patients. In conclusion, female gender, renal dysfunction, and the drug-induced BrS-like ECG morphology may be associated with augmented ECG responses to pilsicainide.

The validity of pharmacokinetic parameters estimated by the maximum a posteriori probability (MAP) Bayesian method was investigated by simulation studies. A 1-compartment model with bolus intravenous administration was used as a pharmacokinetic model, and the coefficients of variation for the parameters and residual error were set at 30% and 10%, respectively. The accuracy of the posterior modes of pharmacokinetic parameters estimated by the MAP Bayesian method was assessed by the difference between the true value and the estimated value. The results showed that the accuracy of the Bayesian estimation depended on sampling times and on the differences between the prior means and individual true parameter values. For assessing the reliability and accuracy of the Bayesian estimation, the authors suggest using the whole posterior distribution of the pharmacokinetic parameters to describe the 95th percentile range for predicted blood concentration profiles. The authors believe that the proposed procedures provide helpful information for evaluating the Bayesian estimation of pharmacokinetic profiles.

シスプラチンによる遅発性悪心・嘔吐の薬物療法に関する文献のシステマティック・レビューを行い、最もエビデンスの高い治療方法を見いだした。総頁数11。

インタビューフォームにおける薬物動態情報の現状を調査し、薬剤師が利用するうえでの問題点を指摘した。総頁数8。

Purpose. To investigate the pharmacokinetics and preventive effects of liver-targeted catalase (CAT) derivatives on hepatic injury caused by reactive oxygen species. Methods. The hepatic uptake of 111In-CAT, galactosylated (Gal-), mannosylated (Man-) and succinylated (Suc-) CAT was investigated in isolated perfused rat livers in a single-pass constant infusion mode. Then, pharmacokinetic parameters were obtained by fitting equations derived from a one-organ pharmacokinetic model to the outflow profile. Their effects in preventing hydrogen peroxide-induced injury were determined by lactate dehydrogenase (LDH) release from the perfused liver. Results. The extraction of CAT derivatives by the liver was dose-dependent, and increased by the chemical modifications described. After being bound to the cell surface, chemically modified CAT derivatives were internalized by the liver faster than CAT. Preperfusion of a CAT derivative significantly reduced LDH release by hydrogen peroxide at least for 30 min, and Man-CAT and Suc-CAT effectively inhibited this release. Conclusions. Internalized CAT derivatives are also effective in degrading hydrogen peroxide and targeted delivery of CAT to liver nonparenchymal cells by mannosylation or succinylation is a useful method for the prevention of hepatic injury caused by reactive oxygen species.

Purpose. The purpose of this study was to clarify quantitatively the contribution of the intestine to the first-pass metabolism of eperisone in rats. Methods. The systemic availabilities of eperisone were estimated by administering the drug into the duodenum, portal vein, and femoral vein in rats in vivo. The first-pass metabolism of eperisone was confirmed in the perfused rat small intestine in situ. Metabolism of eperisone to an omega -1-hydroxylated metabolite (HMO), the first step of eperisone metabolism, was studied using rat intestinal microsomes in vitro, Results. The bioavailabilities in the intestine were 0.176 and 0.0879 at administration rates of 100 and 25 mg/h/kg, respectively, whereas those in the liver were 0.532 and 0.486, respectively. In the intestinal perfusion experiment, the appearance clearance to the portal vein from the intestinal lumen was much lower than the elimination clearance from the intestinal lumen, resulting in high metabolic clearance of eperisone in the small intestine. Eperisone was biotransformed to HMO by rat intestinal microsomes, and this was inhibited by a-naphthoflavone and an anti-rat CYP1A antibody. Conclusions. Those data strongly suggest that eperisone may be metabolized to HMO by CYP1A in rat intestinal microsomes during the first-pass through the epithelium of the small intestine.

Introduction: We investigated the clinical significance of the peritoneal clearance of levofloxacin, which is used to treat exit-site infections caused by Pseudomonas aeruginosa in patients under continuous ambulatory peritoneal dialysis (CAPD), and proposed an optimum dose and dosage interval for treating these patients. Methods: We measured the concentrations of levofloxacin in the plasma, the drainage from peritoneal dialysis and the plasma ultrafiltrate by HPLC in 6 patients receiving CAPD, and determined the plasma unbound fraction (fuB). We also estimated the total clearance (CLtot/F), distribution volume (Vd/F) and peritoneal clearance (CLpd) in each patient. Results: The mean (S. D.) CLtot/F, Vd/F, CLpd, and fuB were 22.6(7.34)ml/min, 76.3(21.9)L, 3.42(0.831)ml/min, and 69.7(13.76)%, respectively. We examined the possible factors affecting the peritoneal clearance of levofloxacin, but did not find any definite trends. Discussion: The average CLpd was about 17% of the CLtot, but in some patients it was above 20%. It seems that the peritoneal clearance values should not be ignored in clinical practice. The minimum plasma concentration of levofloxacin in the steady state in patients under CAPD given 100 mg of levofloxacin every 24 h was 2.7±0.72 μg/ml, which exceeded the MIC50 of the drug for P. aeruginosa. Administration of the drug at a dose of 100 mg every 48 h, a common clinical practice, may not be adequate to maintain a blood concentration high enough to attain an appropriate antibacterial effect.

Purpose, The stereoselective distribution of three basic drugs, disopyramide (DP), flecainide (FLC) and verapamil (VP), was studied to clarify the relationships between the tissue-to-unbound plasma concentration ratio (Kpf) and drug lipophilicity and binding to phosphatidylserine (PhS), which are possible factors determining the tissue distribution of these drug enantiomers. Methods, The drug enantiomer or racemate was administered to rats by intravenous constant infusion. Their concentrations in plasma and tissues were determined using enantioselective high-performance liquid chromatography. Plasma protein binding, and buffer-octanol and buffer-hexane containing PhS partition coefficients were also determined. Results, The stereoselectivity of the tissue-to-plasma concentration ratio (Kp) was partly associated with that of serum protein binding. However, the Kpf value of R(+)-VP in the lung was significantly higher than that of S(-)-VP. A linear correlation was observed between the Kpf values of these drug enantiomers in brain, heart, lung and muscle, and their buffer-hexane containing PhS partition coefficients. The in vitro data for the binding of these drugs to PhS suggest that stereoselective binding of VP to PhS may correspond to its stereoselective tissue binding. Conclusions. Our findings provide some evidence for a role of tissue PhS in the tissue distribution of basic drugs with respect to stereoselectivity of drug enantiomers distribution.

We studied the inhibition of S-warfarin metabolism by nonsteroidal antiinflammatory drugs (NSAIDs) in human liver microsomes in vitro. After screening for potential inhibitors among ten NSAIDs using human recombinant cytochrome P450, inhibition kinetic parameters were estimated using human liver microsomes. Phenylbutazone and bucolome were suggested to increase the unbound steady-state level of S-warfarin about four-and five-fold, respectively, as estimated from these metabolic parameters.

A simple and practical high-performance liquid chromatographic analysis has been developed for measuring teniposide (VM26) in human plasma. The present analytical method has improved extraction efficiency from human plasma, therefore allowing determination of VM26 in a clinical setting using ultraviolet detection alone. Furthermore, sample preparation was simplified and shortened through use of a one-step extraction procedure. VM26 and internal standard (ibuprofen) were extracted from human plasma (0.5 ml) with ethyl acetate. A phenyl mu Bondapak column eluted with a mobile phase, consisting of acetonitrile-distilled water-acetic acid (30:68:2, v/v/v) was used for separation, and quantitation was achieved with a UV monitor set at 240 nm. Average extraction efficiency was 96.8+/-6.6% for VM26 between 1 and 25 mu g/ml, and 91.4+/-4.3% for internal standard, with bath intra-and inter-day coefficients of variation being less than 10%. The detection limit with a 100-mu l injection was estimated at 0.2 mu g/ml with a signal-to-noise ratio of 3 for VM26 in human plasma. The stability data of VM26 in plasma, standard and stock solutions were also obtained. The present method was found to be an alternative to the previously reported method with an electrochemical detection, and can be easily applied to routine clinical pharmacokinetic studies of VM26. (C) 1998 Elsevier Science B.V. All rights reserved.

The renal disposition characteristics of superoxide dismutase (SOD) and its derivatives, including macromolecular conjugates with polyethylene glycol and carboxymethyl-dextran, a cationized derivative, and glycosylated derivatives with galactose and mannose, were studied in the isolated perfused rat kidney. Renal disposition processes, such as glomerular filtration, tubular reabsorption, and uptake from the capillary side, were quantitatively determined by single-pass indicator dilution experiments under filtering and nonfiltering kidney conditions. Native SOD had a high glomerular filtration rate (40% of that of inulin) and was effectively reabsorbed in the tubules, while no significant uptake was observed from capillary side. Macromolecular conjugates showed restricted glomerular filtration due to an increase in molecular size. Cationization of SOD greatly enhanced its association with the tissue, not only from the luminal side but also from the capillary side, based upon electrostatic interaction. Galactosylated and mannosylated SOD showed reduced tubular reabsorption and increased exposure of the luminal surface to the enzyme. In addition, a small but significant uptake of mannosylated SOD from the capillary side was observed. This uptake was dose-dependent and completely inhibited by mannan, suggesting that mannose receptor-mediated endocytosis existed in the capillary side of the kidney. Thus, we can manipulate the renal disposition profiles of son by changing its physicochemical or biological properties through chemical modification.

Therapeutic effect of superoxide dismutase (SOD) and three derivatives: a conjugate with polyethylene glycol (SOD-PEG(2)), a cationized derivative (cSOD), and a mannosylated derivative (Man-SOD), on acute renal failure induced by ischemia/reperfusion was studied in rats. SOD and derivatives were administered intravenously to the rat after nephrectomy of the right kidney and before and after 60 min occlusion of the left renal artery. At 48 hr after reperfusion, the renal function was evaluated by determining the urinary excretion rate of C-14-inulin injected intravenously. No therapeutic effect on the impaired renal function was shown in the case of low dose SOD (2600 unit/kg) treatment. In contrast, administration of cSOD which was shown to be taken up by the isolated perfused kidney from its capillary side and SOD-PEG(2) which maintained high plasma concentration exhibited significant therapeutic effect, as did SOD at ten-fold higher dose (26,000 unit/kg). On the other hand, renal damage was promoted by Man-SOD. Thus, the present study demonstrated that chemical modification may improve the therapeutic effect of SOD on the ischemic acute renal failure and increased SOD concentration in the renal vascular space is an important factor for the improved effect.

To construct the strategy to control the renal disposition profiles of protein drugs by chemical modification, studies were performed using the perfused rat kidney. Renal disposition processes, i.e., glomerular filtration, tubular reabsorption, and uptake from the vascular side, were quantitatively determined by single-pass indicator dilution experiments under filtering and non-filtering conditions. As the first step, the renal disposition characteristics of model protein drugs and macromolecules were evaluated. These studies clarified the relationship between physicochemical properties of macromolecules, such as molecular weight and electric charge, and their fate in the kidney in a quantitative manner. Based on these findings, an antioxidant enzyme, superoxide dismutase (SOD), selected as a therapeutic agent for various tissue injuries including renal failure mediated by reactive oxygen species, was chemically modified. Conjugation with macromolecules, polyethylene glycol and carboxymethyl dextran, decreased glomerular filtration of SOD. Cationization enabled the enzyme to distribute to the kidney from the capillary side and to be completely reabsorbed by the tubular epithelium after glomerular filtration based on electrostatic interaction. On the other hand, glycosylation with monosaccharides, galactose and mannose, significantly reduced its tubular reabsorption and enhanced its exposure to the luminal surface. Furthermore, the mannosylated derivative accumulated in the kidney from the vascular side via a mannose-recognition mechanism. Thus, the present study demonstrates that chemical modification is useful for the control of renal disposition characteristics of protein drugs.

The renal disposition characteristics of In-111-labeled neocarzinostatin (NCS), soybean trypsin inhibitor (STI), and superoxide dismutase (SOD) were studied in the perfused rat kidney. In a single-pass indicator dilution experiment, venous and urinary recovery profiles and tissue accumulation of proteins were determined under filtering or nonfiltering conditions. In the nonfiltering kidney perfusion experiment, no significant tissue accumulation was observed, suggesting minimal uptake from the glomerular and peritubular capillary sides. Therefore, tissue recovery corresponded to that with tubular reabsorption after glomerular filtration. The total amount of NCS or STI being filtrated through glomeruli, the sum of tissue and urinary recoveries, was similar to that of inulin, but that of SOD was about half. Similarly, the steady-state distribution volumes (V(d)) of NCS and STI obtained by moment analysis of their venous outflow curves were similar to that of inulin, while the V(d) value of SOD was significantly lower. These results suggest the restricted passage of SOD through the glomerular and postglomerular capillary wall. The tubular reabsorption ratio of proteins against the total filtrated amount decreased with an increase in the administered dose, suggesting nonlinearity of reabsorption. SOD had the largest reabsorption ratio. Thus, this experimental system is useful for quantitative analysis of renal disposition of proteins.

The disposition characteristics of model macromolecules such as dextran (70 kDa), bovine serum albumin (BSA), and their charged derivatives were studied in the perfused rat kidney. In a single-pass indicator dilution experiment, venous and urinary recovery patterns and tissue accumulation of radiolabeled compounds were evaluated under filtering or nonfiltering conditions. In the filtering kidney, cationic macromolecules such as diethylaminoethyl-dextran (DEAE-dex) and cationized BSA (cBSA) accumulated in the kidney to a great extent whereas anionic and neutral macromolecules such as BSA, carboxymethyl-dextran (CM-dex), and dextran showed only small uptake. DEAE-dex and cBSA were distributed to both the medulla and cortex regions of the kidney and their recoveries in the kidney decreased as the injected dose increased. Similar tissue uptake was observed in the nonfiltering kidney perfusion system suggesting that they were mainly taken up by the kidney from the renal capillary side based on electrostatic interaction. In addition, the steady-state distribution volumes of cationic macromolecules calculated from venous outflow patterns were larger than those of the intravascular volume estimated from the distribution volumes of neutral and anionic macromolecules, suggesting their reversible interaction with the vascular wall. On the other hand, dextran derivatives with molecular weight distribution were excreted into urine based on glomerular permselectivity; i.e., cationic DEAE-dex and anionic CM-dex showed enhanced and restricted urinary excretion, respectively, compared with neutral dextran. In contrast, no significant excretion was observed for BSA and cBSA. The utility of the isolated rat kidney perfusion experiment for studying the renal disposition of macromolecular drugs was thus demonstrated.

The effect of electric charge on the hepatic disposition of macromolecules was studied in the rat. Charged derivatives of dextran (T-70) and bovine serum albumin (BSA), mitomycin C-dextran conjugates (MMC-D), and lactosaminated BSA (Lac-BSA) were employed as model macromolecules. After intravenous injection, cationic macromolecules were rapidly eliminated from plasma because of their extensive hepatic uptake, while anionic and neutral macromolecules were slowly eliminated. Cationic macromolecules were recovered from parenchymal and nonparenchymal hepatic cells at a cellular uptake (per unit cell number) ratio of 1.4-3.2, while that of Lac-BSA was 14. During liver perfusion using a single-pass constant infusion mode, cationic macromolecules were continuously extracted by the liver, with extraction ratios at steady-state (E(ss)) ranging between 0.03 and 0.54, whereas anionic and neutral macromolecules were almost completely recovered in the outflow at steady state. The E(ss) for cationized BSA (Cat-BSA) and cationic MMC-Dcat were concentration dependent and decreased at low temperatures and in the presence of colchicine and cytochalasin B. The possible participation of the internalization process in the uptake of cationic macromolecules by hepatocytes was suggested.