International journal of clinical pharmacology, therapy, and toxicology最新文献

Since immunosuppressed patients are at higher risk of serious influenza virus infection than healthy subjects, we decided to study the serological effectiveness of influenza vaccination on renal transplant patients, despite the theoretical aspect that such treatment could induce glomerular lesions through an immunological process. Forty transplant patients aged from 20 to 50 years with well functioning renal graft and no febrile episode were studied. Blood samples were collected before the intramuscular injection of 0.5 ml of multivalent influenza vaccine (PASTEUR MERIEUX SERUM VACCINS), at one and at two months after the vaccination. Before vaccination, the antibody titers to influenza virus ranged from 0 to 1/20 and after vaccination from 1/20 to 1/320. One month after vaccination 17/40 (42.5%), 18/31 (58%) and 16/33 (48%) patients showed a four-fold or greater increase of serum influenza antibody titers to antigens A/H3N2, A/H1N1 and B, respectively. A similar response at two months in relation to the first month response rate after vaccination was found in 15/17 (88%), 18/18 (100%), and 15/16 (93%) of transplant patients for the above mentioned three antigens. Side-effects were observed in two of the studied patients. Serum creatinine and urine protein were not changed. Also acute graft rejection episodes were not observed. It is suggested that influenza vaccination is safe and serologically effective on renal transplant patients.

Pharmacokinetic measurements were performed in two groups of patients with coronary heart disease (CHD) after single and multiple dosing of 2 mg linsidomine (SIN 1). The drug was administered by intravenous short time infusion in 12 CHD-patients with renal insufficiency (RI group, Clcr: 11 +/- 6 ml/min) and in 12 CHD-patients with normal kidney function (control group, Clcr: 88 +/- 22 ml/min). The measurement of plasma concentration time courses of total SIN 1C (SIN 1 + SIN 1C) was found to be suitable for an estimation of the SIN 1C related half-life of the terminal phase (t50% = 1.5 +/- 0.5 h), as SIN 1 was eliminated from plasma rapidly (t50% = 12 to 20 min). Furthermore, the mean total SIN 1C plasma profiles were equal after single and multiple administration of the drug giving evidence that SIN 1C is not accumulating during repetitive dosing of SIN 1 in patients with renal disease. The mean maximum renal fraction of total SIN 1C excretion of RI-subjects (fe = 0.8 +/- 0.8% of dose) was significantly different from the corresponding mean value of the control group (fe(N) = 5.8 +/- 5.1% of dose). No differences were found for fe and fe(N) between day 1 and day 4. As SIN 1 is degraded in plasma very rapidly and as SIN 1C is cleared mainly extrarenally, any restrictions concerning repetitive SIN 1 dosage regimen should not be considered for CHD-patients with renal failure.

Cocaine abuse is widespread in North America. It is estimated that almost one in every four Americans has used cocaine at least once in his/her lifetime. In the past two decades, cocaine related cardiovascular complications have mushroomed because cocaine has become cheaper and more readily available. The fundamental effects of cocaine on cardiovascular system are similar to those observed following an intense, sympathetic stimulation. Cocaine intake results in marked increase in blood pressure, myocardial oxygen demand and heart rate. Coronary blood flow, which increases in response to exercise (endogenous sympathetic stimulation) however, is decreased by cocaine intake. Increased demand of oxygen by the myocardium in the face of decreased supply in subjects with cocaine use, leads to myocardial ischemia, which in turn forms a substrate for most of the cardiovascular complications, namely, myocardial infarction, cardiac arrhythmias and acute pulmonary edema. Hypertension related complications, dissection and rupture of aortic aneurysm, hemorrhagic stroke, in addition to infective endocarditis, myocarditis, cardiomyopathy all occur more frequently in cocaine addicts. In this review, pertinent clinical pharmacology and cardiovascular risks associated with cocaine abuse are presented.

Alfuzosin is a new alpha 1-adrenoceptor antagonist particularly effective in the symptomatic treatment of benign prostatic hypertrophy (BPH). The elimination of alfuzosin being almost entirely metabolic, the potential pharmacokinetic interaction with cimetidine (H2-receptor antagonist) was investigated in 10 healthy young subjects. Pharmacokinetics of alfuzosin were appraised as a 5 mg oral dose before, after one day and after 20 days of cimetidine (1 g/d) administration. An inhibition of the hepatic mixed function oxidase system by cimetidine was established by the oral antipyrine clearance test. Under these conditions, alfuzosin pharmacokinetics were only marginally affected by concomitant cimetidine administration. Surprisingly, a significantly shorter elimination half-life was found after 20 days on cimetidine (from 5.1 +/- 0.4 h to 4.4 +/- 0.5 h). This fact must be attributed to the large inter-individual variation in pharmacokinetic parameters reported for alfuzosin. Cmax and AUC increased up to 20% after cimetidine but without statistical significance. No side-effects on the association cimetidine-alfuzosin were reported. In conclusion, there is a lack of pharmacokinetic interaction on cimetidine-alfuzosin co-administration.

In the previous study, we determined the in vivo binding parameters of valproic acid to serum proteins in seven healthy young adults at steady-state. In this study, we determined the effects of serum protein binding on hepatic elimination with the use of observed data obtained from our previous study of valproic acid. A regression analysis between the binding parameters and the pharmacokinetic parameters was performed. In addition, the relationship between each pharmacokinetic parameter was also analyzed. The order of association constant (K) for valproic acid-serum protein was 10(-2) l/mumol. No significant correlation was found between the binding parameters and the rate of elimination. On the other hand, the average unbound serum concentration was found to be a significantly negative correlation with the unbound (intrinsic) clearance (p = 0.0082). The product of association constant and concentration of free protein (P) correlated positively with the unbound clearance (p = 0.0233) and negatively with the average unbound and total serum concentrations (p = 0.0021 and p = 0.0029, respectively). The results indicate that the membrane permeability of valproic acid is high and that the increase of unbound clearance accompanies directly the decrease of the average unbound and total serum concentrations. Consequently, the KP values are proportional to the unbound clearance due to the rapid changes of the concentration of free protein. Therefore, the dissociation of the valproic acid-serum protein complex is not a rate-limiting factor for hepatic elimination and hence the serum protein binding cannot limit the ability of the liver to extract drug from blood.

Food-induced changes on the bioavailability of a sustained-release theophylline tablet, which uses acrylic resins Eudragit as sustaining agent, were studied in 12 healthy male volunteers. The tablet was developed in our laboratory using conventional technology. It presented a good bioavailability pattern and maintained plasmatic concentrations within the therapeutic range for 12 hours under conditions of steady-state. The study design was a 4 x 4 latin square involving 12 subjects who received a single dose of the tablet while fasting or with a standardized normal, high fat or high fat/high protein meal. The results showed no differences in AUC, K, tmax, ka and MRT. Statistical differences were found in Cmax comparing the fasting condition with high fat/high protein diet. A delay was also observed in the detection of the drug in plasma when the tablet was administered with high fat and high fat/high protein food, but clinically the changes seem to be irrelevant.

Plasma kinetics of netilmicin, an aminoglycoside antibiotic was studied in 62 patients undergoing urologic surgery. Despite the use of a standard 100 mg-dose, no toxic levels were achieved except in one patient. A poor correlation was found between netilmicin plasma elimination constant and creatinine clearance (r = 0.34, p = NS). We can conclude that the prediction of netilmicin plasma concentrations is not possible using only demographic patient's data. The monitoring of netilmicin levels should be performed in long-term treatments but not in 4-dose regimes such as in urologic prophylaxis.

Two new bioavailability parameters were recently suggested [Koeleman et al. 1991] to define (i) the time that the concentration in the blood stays above a defined minimum effective concentration, te and (ii) the onset of the effect, to. In addition to conventional bioequivalence parameters, the new bioavailabilty parameters (to and te) were calculated in this study and statistically compared for penicillin, chloroquine, oxytetracycline, amoxycillin and flucloxacillin from available bioequivalence data. For oxytetracycline, flucloxacillin and amoxycillin, the conventional bioavailability parameters indicated partial equivalence whereas using the te and to parameters, more realistic indications of the possible extent of the performance of a drug from dosage forms were obtained than with the conventional bioequivalence parameters. The new parameters gave additional information for a better evaluation of the performance of a drug from a dosage form.

Plasma concentration and PR-interval prolongation were correlated after a single dose of 80 mg verapamil (trial A) and at steady-state during one dose interval (80 mg verapamil t.i.d.) on day 7 (trial B) and day 14 (trial C) and the subsequent dose interval at the afternoon on day 14 (trial D). The pharmacokinetic parameters of verapamil indicated a two-fold increase in AUC and Cmax at trial B and C when compared with the single dose application, but AUC and Cmax were considerably lesser during the afternoon dosing interval (trial D). For each subject, concentration/effect analysis was established: according to a linear and a sigmoidal model, and using a plasma concentration vs effect approach (1) and a semiparametric effect-site concentration vs effect approach (2). The comparison of the two different approaches and models showed that in general, the concentration/effect analysis based on the linear model and with approach 2 gave the best description of the dromotropic response to verapamil for the majority of the individuals. However, approach 1 accounts for 30 to 50% of the concentration/effect curve established in the data subsets of trial A to D, and about 40% of all curves in trial A, B and C can be more precisely described with the Emax-model, whereas almost all curves obtained in trial D were best described by a linear model. A decrease in the responsiveness to verapamil at steady-state was indicated by both models, but more precisely described by the parameters of the Emax-model.

Ipratropium bromide (IB) is a non-selective muscarinic antagonist, whose bronchodilator efficacy has been shown in reversible and irreversible obstructive airway diseases. Pirenzepine is a M1 receptor antagonist and effective in vagally-induced bronchoconstriction. To investigate the bronchodilator efficacy of nebulized pirenzepine, we compared nebulized pirenzepine with nebulized IB and nebulized isotonic saline (placebo). Eighteen patients with reversible and 18 patients with irreversible obstructive airway disease were studied. Nebulized isotonic saline (placebo), 100 mcg nebulized pirenzepine and 125 mcg nebulized IB were given on three consecutive days. Spirometry was performed prior to nebulization and repeated at 5, 30, 60, 90 and 120 minutes following nebulized medication. A dose of 125 mcg IB resulted in a significant increase in FEV1 in patients with both reversible or irreversible bronchoconstriction (p < 0.00001, p < 0.03). IB at the same dose resulted in an increase in FVC in patients with irreversible bronchoconstriction (p < 0.001) and an increase in FEF25-75 in patients with reversible bronchoconstriction (p < 0.0003). Pirenzepine therapy resulted in no significant change in the same parameters. It is concluded that nebulized pirenzepine at a dose of 100 mcg does not have bronchodilator effect in patients with reversible or irreversible bronchoconstriction.