Effect of buffering on pharmacokinetics of ketoprofen enantiomers in man

Aims Concomitant administration of magnesium hydroxide may affect the rate or extent of absorption of non-steroidal anti-inflammatory drugs. In order to find out whether or not buffering modifies the pharmacokinetics of ketoprofen, plasma concentration-time courses resulting from oral administration of unbuffered formulations were compared with those of buffered formulations.
Methods Two groups of 12 healthy and young male subjects were included in two randomized cross-over studies and received single oral doses of ketoprofen 12.5 or 25  mg, respectively, given as tablets which were either unbuffered or buffered with magnesium hydroxide/citrate. Ketoprofen enantiomers in plasma were determined by h.p.l.c. up to 24  h post-dose.
Results Maximum plasma concentrations ( C _max ) of both the (R)- and (S)-enantiomer, observed after administration of the buffered formulations (12.5 and 25  mg), were higher compared with the unbuffered tablets by about 50–80%. The area under concentration-time data (AUC) was unaffected, and, hence, C _max/AUC was increased by buffering. Time to C _max ( t _max ) and mean residence time (MRT) tended to be or was shortened by buffering.
Conclusions It is concluded that buffering of two ketoprofen formulations with magnesium hydroxide/citrate enhanced the concentration maximum by increasing the rate of absorption and leaving AUC unaffected.     

赛赓啶对 KBV200细胞多药抗性的逆转作用

研究赛赓啶对KB_V200细胞多药抗性的逆转作用及逆转机制。在KB_V200细胞,采用MTT法,测出赛赓啶对长春新碱、阿霉素和鬼臼乙叉甙耐药的逆转系数分别为5.5,2.0和1.9,而对5-氟尿嘧啶、美法仑的细胞毒性作用无明显影响,表明赛赓啶为多药抗性逆转剂。荧光分光光度法测定表明,赛赓啶可使KB_V200细胞内阿霉素蓄积量增加。流式细胞荧光测定显示赛赓啶可增加罗丹明123的蓄积并减慢其外排。免疫细胞化学及狭缝杂交表明赛赓啶不影响KB_V200细胞的P-糖蛋白染色深度和 mdr1 RNA 表达水平。以上结果提示赛赓啶的多药抗性逆转机制是抑制P-糖蛋白泵的功能。     

MAO-A inhibition in brain after dosing with esuprone, moclobemide and placebo in healthy volunteers: in vivo studies with positron emission tomography

Objective: The aim of the study was to investigate whether or not esuprone binds substantially to MAO-A in the human brain. Methods: In a randomised double-blind placebo-controlled study 16 male healthy volunteers were examined␣with positron emission tomography (PET) with [¹¹C]harmine. Eight of the volunteers were given daily doses of 800 mg esuprone, four were given bi-daily doses of 300 mg moclobemide, and four volunteers were given placebo tablets. PET was performed before initiation of a 7-day treatment period. On day 7, one investigation was made immediately before administration of the drug, representing 23 h after the previous day's treatment for esuprone and 11 h after the last tablets of moclobemide. Further investigations were made 4 h and 8 h after the morning dose on day 7. Results: PET showed a high degree of binding of [¹¹C]harmine, a high-affinity ligand for MAO-A, before the start of treatment, and a marked and similar reduction after treatment with esuprone and moclobemide. A slight tendency for normalisation of enzyme binding was observed at the last time point. In the placebo group no change was observed. Plasma kinetics of esuprone showed a rapid elimination with a half-life of about 4 h. Conclusion: The study demonstrates that esuprone was comparable to moclobemide in its effect on MAO-A inhibition in the brain at the doses given. This is an illustration of the potential of PET to monitor drug effects directly on target biochemical systems in the brain in human volunteers, and the possibility of using these data, rather than pharmacokinetic data, for the determination of dosing intervals. Received: 21 August 1996 / Accepted in revised form: 22 November 1996     

Synthesis and Evaluation of Azole-Substituted Tetrahydronaphthalenes as Inhibitors of P450 arom,P450 17, and P450 TxA2

In search of potential drugs for the treatment of estrogen- and androgen-dependent cancer as well as the prophylaxis of metastases, tetralones, tetralins, and dihydronaphthalenes bearing a OCH₃ substituent at the benzene nucleus and an imidazol-4-yl, imidazol-1-yl, or 1,2,4-triazol-1-yl substituent in 2-position were synthesized with and without C₁-spacer between the rings (compounds 2 – 26 ). The compounds were tested in vitro for inhibition of the three target enzymes P450 arom (human placental microsomes), P450 17 (rat testicular microsomes), and P450 TxA₂ (citrated human whole blood). To examine selectivity, some compounds were further tested in vitro for inhibition of P450 18 (bovine adrenal mitochondria), P450 see (bovine adrenal mitochondria) and corticoid formation (aldosterone, corticosterone; ACTH stimulated rat adrenal tissue). In vivo, selected compounds were examined in Sprague Dawley rats regarding P450 TxA₂ inhibition, reduction of plasma testosterone concentration, antiuterotrophic activity (inhibition of the uterotrophic activity of androstenedione), reduction of plasma estradiol concentration (pregnant mares' serum gonadotropin-primed rats), and mammary tumor inhibiting activity (dimethylbenzanthracene-induced tumor; pre- and postmenopausal model). In the series of imidazol-4-yl compounds, which represent a novelty in the field of azole inhibitors of steroidogenic P450 enzymes, strong inhibitors of P450 arom and/or P450 17 were found: 7-OCH₃-2-(imidazol-4-ylmethylene)-1-tetralone ( 4 ) and 7-OCH₃-2-(imidazol-4-ylmethyl)-tetralin ( 12 ) are among the most potent inhibitors of P450 arom in vitro known so far. Compound 4 is a selective inhibitor, whereas 12 shows in addition strong inhibition of P450 17. In contrast to 12 , the 6-OCH₃ derivative (compound 11 ) is a selective inhibitor of P450 17, being 50 times more potent than ketoconazole. Some imidazol-1-yl compounds show a marked inhibition of P450 TxA₂: 2-(imidazol-1-ylmethyl)-1-tetralone ( 13 ) is a selective inhibitor of P450 TxA₂, whereas 7-OCH₃-2-(imidazol-1-ylmethyl)-tetralin ( 17 ) as well as 2-(imidazol-1-ylmethyl)-tetralin ( 16 ) and 7-OCH₃-2-imidazol-1-yl-3,4-dihydronaphthalene ( 25 ) additionally show strong inhibition of P450 arom and P450 17. Regarding the other steroidogenic P450 enzymes as well as corticosterone formation, the compounds show only little inhibitory activity. Aldosterone formation, however, is inhibited at low concentrations. Nevertheless, 4 and 12 are more selective, i.e. inhibit aldosterone synthesis less than the well known inhibitor of P450 arom fadrozole. The compounds show activity in the aforementioned in vivo tests.     

Therapeutic traditions in type 2 diabetes — are they changing?

The utilisation of antidiabetic drugs reflects both the prevalence of diabetes and the different therapeutic traditions of physicians. A questionnaire survey to study attitudes to the use of oral antidiabetic drugs amongst physicians and possible changes in treatment habits was carried out in a representative sample of Finnish physicians (n=454) in 1992 and the results were compared with those of a similar survey carried out in 1985, and with drug utilisation statistics.The mean fasting blood glucose level at which a physician would start pharmacological treatment was 8.7 mmol·l^–1, which was significantly lower than in the 1985 survey. The responses to various case histories suggested a more active approach to pharmacological treatment compared to the 1985 survey. Insulin treatment especially seems to have gained in popularity. This change in attitude was paralled by an increase in the consumption of antidiabetic drugs in Finland during the observation period. The increase in use of oral drugs was steeper in Finland than in Norway and Sweden.Whether this active approach will improve the metabolic control and prognosis of patients with Type 2 diabetes, remains to be demonstrated.     

Involvement of synthesis of brain cell structural proteins in the action of antitheines on long-term memory

Academician S. V. Anichkov Department of Pharmacology, Research Institute of Experimental Medicine, Academy of Medical Sciences, St. Petersburg. (Presented by Academician of the Academy of Medical Sciences A. N. Klimov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 113, No. 5, pp. 506–508, May, 1992.     

解毒保肾汤治疗早期糖尿病性肾病

[目的 ]观察解毒保肾汤治疗早期糖尿病性肾病的疗效 .[方法 ]将诊断为早期糖尿病性肾病的病人随机分为 2组 ,其中治疗组 4 4例给予解毒保肾汤 ,对照组 2 0例给予阳性对照药络汀新 ,观察治疗前后 2组病人的临床症状、空腹血糖、糖化血红蛋白量及尿蛋白排泄率等的变化 .[结果 ]治疗组总有效率为 80 % ,对照组总有效率为 6 5 % ,治疗组疗效优于对照组 ;治疗组在改善临床症状 ,降低空腹血糖、糖化血红蛋白量及尿蛋白排泄率等方面均优于对照组 .[结论 ]解毒保肾汤能够降低早期糖尿病性肾病患者的血糖、减少尿蛋白的排泄 ,具有一定的保护肾脏功能 ,对早期糖尿病性肾病有治疗作用 .     

中西药合用对帕金森病大鼠旋转行为的影响

目的 观察中西药合用对帕金森病(Parkinson disease，PD)大鼠旋转行为的影响。方法 采用6羟多巴胺注射于脑右侧黑质造成偏侧帕金森病模型，并用滋补肝肾、通络解毒的中药以及西药美多巴进行治疗，同时设立美多巴对照组，观察中西药合用对PD大鼠旋转行为的影响。结果 中西药合用可使模型大鼠的旋转圈数明显减少。结论 中西药合用能明显改善PD模型大鼠的旋转行为。     

RGD-based strategies for selective delivery of therapeutics and imaging agents to the tumour vasculature

During the past decade, RGD-peptides have become a popular tool for the targeting of drugs and imaging agents to alphavbeta3-integrin expressing tumour vasculature. RGD-peptides have been introduced by recombinant means into therapeutic proteins and viruses. Chemical means have been applied to couple RGD-peptides and RGD-mimetics to liposomes, polymers, peptides, small molecule drugs and radiotracers. Some of these products show impressive results in preclinical animal models and a RGD targeted radiotracer has already successfully been tested in humans for the visualization of alphavbeta3-integrin, which demonstrates the feasibility of this approach. This review will summarize the structural requirements for RGD-peptides and RGD-mimetics as ligands for alphavbeta3. We will show how they have been introduced in the various types of constructs by chemical and recombinant techniques. The importance of multivalent RGD-constructs for high affinity binding and internalization will be highlighted. Furthermore the in vitro and in vivo efficacy of RGD-targeted therapeutics and diagnostics reported in recent years will be reviewed.     

Assessment of Rhythm and Rate Control in Patients with Atrial Fibrillation

A recent series of randomized prospective clinical trials that compared rate control with rhythm control in patients with atrial fibrillation (AF) found no significant difference in primary outcome between the two strategies. However, these trials lacked clear criteria for defining "successful" rate or rhythm control. Various measures have been used to gauge the success of antiarrhythmic drug therapy, including time to first recurrence of AF, any AF recurrence, AF burden, and a reduction in symptoms. Determining the success of antiarrhythmic therapy can be relatively straightforward by using how patients feel during therapy as a key endpoint. Most patients are satisfied with a major reduction in symptomatic AF episodes and can live comfortably with occasional episodes of AF. For those who are bothered by even infrequent, brief AF episodes, a treatment regimen that eliminates nearly all AF recurrences is required, although often hard to achieve. Catheter ablation may be necessary to achieve a successful outcome in these patients. Suppression of AF in a patient at high risk of stroke does not, however, remove the need for concomitant warfarin therapy. The endpoints of ventricular rate control are not clear, and the recently published rhythm versus rate control trials lacked standard criteria for judging acceptable rate control. One relatively simple method is to try and achieve a 24-hour heart rate that mimics expected normal sinus rhythm. It is important to achieve good rate control to minimize symptoms and the risk of tachycardia-mediated cardiomyopathy.