Разработан метод количественного определения азитромицина для ВЭЖХ с масс-спектрометрическим детектированием. Предел обнаружения препарата составляет 0,5 нг/мл. Метод был применен для изучения фармакокинетики и биоэквивалентности препарата Азитромицин (капсулы по 250 мг отечественного производства) в сравнении с препаратом Сумамед ® (аналогичная лекарственная форма производства компании «Плива», Хорватия). Фармакокинетическое исследование проводилось открытым перекрестным рандомизированным методом. В исследование были включены 18 добровольцев. Были рассчитаны фармакокинетические параметры, необходимые для оценки биоэквивалентности изучаемого препарата. Статистический анализ параметров фармакокинетики показал биоэквивалентность препаратов Азитромицин и Сумамед.

Сравнение биодоступности двух лекарственных форм фампридина – фампридин, таблетки пролонгированного высвобождения 10 мг (исследуемый препарат, ОАО «Валента Фармацевтика», Россия) и фампира, таблетки пролонгированного высвобождения 10 мг (референтный препарат, Biogen Idec Ltd, Великобритания) было осуществлено при проведении открытого, рандомизированного, перекрестного исследования однократного применения исследуемых препаратов в дозе 10 мг. Средние значения (± SD) показателя Cmax составили (27,28 ± 4,33) нг/мл для референтного препарата и (26,63 ± 3,44) нг/мл для исследуемого препарата. Средние значения для показателя AUC составили (302,56 ± 56,23) и (300,57 ± 55,24) нг · ч/мл соответственно. 90 % доверительный интервал для отношения средних геометрических параметров Cmax и AUC находился в диапазоне 91 – 105 % для Cmax и в диапазоне 90 – 109 % для AUC. Границы рассчитанных 90 % доверительных интервалов находились в пределах допустимых (80 – 125 %), что соответствует требованиям для подтверждения биоэквивалентности исследуемых препаратов.

Pharmacokinetics of the actoprotector Metaprot, an original Russian drug, has been studied in a group of healthy adult volunteers. Metaprot in capsules was administrated orally as a single dose of 250 mg. The concentration of the active substance (ethylthiobenzimidazole) in the blood serum was determined by high-performance liquid chromatography (HPLC) with UV detection. The pharmacokinetic parameters were calculated by the model-independent method. The peak concentration of ethylthiobenzimidazole in plasma was Cmax = 0.91 +/- 1.05 microg/ml and the average time to peak concentration was t(max) = 1.06 +/- 0.16 h. A polymodal character of the distribution of pharmacokinetic parameters in the test group was revealed.

An open randomized crossover test on 18 healthy volunteers was used to study the pharmacokinetics of anvifen (acting substance, aminophenylbutyric acid) manufactured in capsules at the Joint-Stock Company "Antiviral" (Russia). The test was performed after single peroral administration in comparison with phenibut tablets of the same manufacturer. The concentration of unchanged aminophenylbutiric acid in the blood plasma was measured by HPLC with UV detection. It is established that anvifen and phenibut are bioequivalent in terms of pharmacokinetics.

Открытым рандомизированным перекрестным методом у 18 здоровых добровольцев изучена фармакокинетика анвифена (действующее вещество - аминофенилмасляная кислота) в капсулах производства ЗАО НПО Антивирал (Россия) после однократного приема в сравнении с таблетками Фенибут того же производителя. Концентрацию неизмененной аминофенилмасляной кислоты в плазме крови измеряли методом ВЭЖХ с УФ-детектированием. Установлено, что Анвифен и Фенибут биоэквивалентны.

Comparative pharmacokinetics of anti-influenza drug composition Antigrippin-maximum administered in capsules and a powder for preparing solutions has been studied after single administraton in a group of 18 healthy volunteers. Both preparations [manufactured by the Antiviral Research and Production Corporation (St Petersbutg) contain 6 active components, including paracetamol, rimantadine, loratadine, ascorbic acid, calcium gluconate, and rutoside in equal amounts. The concentrations of unchanged paracetamol, rimantadine, and loratadine in the blood plasma were degtermined by HPLC with mass-spectrometric and UV detection. The pharmacokinetic parameters of allindicated active components exhibited no detectable distinctions, except for the time to attaining maximum concentration ofparacetamol and the value of the maximum concentration of loratadine.

Pharmacokinetics of the actoprotector Metaprot, an original Russian drug, has been studied in a group of healthy adult volunteers. Metaprot in capsules was administrated orally as a single dose of 250 mg. The concentration of the active substance (ethylthiobenzimidazole) in the blood serum was determined by high-performance liquid chromatography (HPLC) with UV detection. The pharmacokinetic parameters were calculated by the model-independent method. The peak concentration of ethylthiobenzimidazole in plasma was Cmax = 0.91 ± 1.05 μg/ml and the average time to peak concentration was tmax = 1.06 ± 0.16 h. A polymodal character of the distribution of pharmacokinetic parameters in the test group was revealed.

Aim. To compare the pharmacokinetics and pharmacodynamics of verapamil retard, regularly taken by patients with Stage I-II arterial hypertension (AH). Material and methods. The effects of the administration time (morning vs. evening) on verapamil retard pharmacokinetics were investigated. This open, randomised, cross-over study included 14 patients with Stage I-II AH, who were regularly administered verapamil retard for 3 weeks. Before the active therapy started, all antihypertensive medications were withdrawn, with an exception of short-acting agents (“wash-out” period). Two weeks later, the patients were administered verapamil retard, according to the randomisation scheme, and were recommended to take one tablet in the morning or evening, at the same time every day. The first administration was at the clinic, under medical supervision. Three weeks later, the participants were hospitalised for pharmacokinetics assessment. Seven days after the end of the first treatment course, a second course started, with an inverted time of verapamil retard administration. Blood concentration of non-modified verapamil was measured by high-performance liquid chromatography with fluorescent detection. Results. Significant differences in pharmacokinetics were observed for morning vs. evening verapamil administration. The respective maximal verapamil concentrations were 239,7±152,3 vs. 148,6±107,4 ng/ml (p<0,01), and respective half-life times were 12,50±3,48 vs. 22,57±15,24 hours (p<0,05). For other parameters, the difference was non-significant. Conclusion. In Stage I-II AH patients, the morning administration of Isoptin SR resulted in accelerated increase of its plasma concentration. At the same time, the evening administration was associated with increased half-life time and higher “concentration-effect” correlation, which makes the latter variant more rational.

For comparative study of the pharmacokinetics of Cemidexor (capsules of 100 mg) and Suprax (capsules of 400 mg), a method of HPLC with quantitative determination of cefixime (the active substance in the drugs) in the blood plasma of patients with UV detection was developed. The data teproducibility with an account of the admissibility criterion was observed within the interval of all the concentrations (0.06-10 mcg/ml). The accuracy and correctness of the method also corresponded to the admissibility criteria. The lower limit of the quantitative determimation of the cefexime blood plasma levels was 0.06 mcg/ml. The pharmacokinetics was studied with the open crossed randomized method. The results were used for calculation of the pharmacokinetic parameters required for estimation of the bioequivalence of the drugs. The statistical analysis of the pharmacokinetic parameters showed that Cemidoxor and Suprax were bioequivalent.

Aim. To study clinical equivalence of original (DilatrendR, ≪Hoffmann-La Roche≫, Switzerland) and of generic (VedicardolR, ≪Synthesis≫, Russia) carvedilols with estimation of their serum level. And to study pharmacoeconomic advantages of their usage in patients with arterial hypertension (HT) of 1-2 stages. Material and methods. Study was double blind, randomized, crossed. 30 patients (8 men and 22 women, 57 y.o. average) with HT of 1 stage (3,3 %) and 2 stage (96,7 %) were included in the study. Original or generic carvedilols (12,5 mg twice a day) were prescribed to the patients. Hydrochlorothiazide was added followed carvedilol dose enlargement if initial antihypertensive effect had been insufficient. The second similar course of therapy with other carvedilol took place in 2 weeks after cancellation of the first carvedilol. Carvedilol serum level, blood pressure (BP), heart rate (HR) and side effects were registered on each visit. Results. 75 % of Vedikardol-group patients and 75 % of Dilatrend-group patients had reached target BP level (<140/90 mm Hg). Monotherapy was effective more than in a half of patients in both groups. Dilatrend had more expressed influence on HR in comparison with Vedikardol. Both drugs did not differ significantly in frequency and intensity of side effects. Conclusion. Generic carvedilol (VedicardolR) has clinical efficiency and pharmacokinetics similar to these of original carvedilol (DilatrendR). Generic carvedilol has lower cost of treatment than this in original carvedilol.

Aim. To compare antiplatelet effect of two acetylsalicylic acid medicines, Acecardol (Synthesis Co. Ltd, Russia) and Aspirin cardio («Bayer AG», Germany), in patients with arterial hypertension (AH) 1-2 stage with increased risk of cardiovascular events. Material and methods. The study was double-blind, randomized, cross-over one. 32 hypertensive patients (12 men and 20 women) aged 59,4 ± 14,4 y.o. were included in the study. They took investigated ASA medicines one after another during 4 weeks each. Antiplatelet efficacy of ASA medicines were estimated by effects on spontaneous and ADP-induced platelet aggregation at every visit. Results. 4-week therapy with both ASA medicines did not have significant effects on spontaneous platelet aggregation and the aggregation induced with low ADP concentrations (0,5 and 1,0 µM). However platelet aggregation induced with ADP in concentration of 2 µM was significantly reduced by therapies. There were not significant inter-group differences. Conclusion. ASA generic medicine Acecardol (Synthesis Co.Ltd., Russia) and original medicine Aspirin cardio («Bayer AG», Germany) are equivalent on antiplatelet effect.

Aim. To study clinical equivalence of two amlodipines under the control of their plasma levels and evaluate their pharmacoeconomical efficacy in patients with arterial hypertension (AH). Material and methods. 31 patient with AH were included in the study (14 men and 17 women). 21 (66 %) patients had AH of 1 stage and 10 (34 %) patients had AH of 2 stage. All patients were 39-81 y.o. (average - 60 y.o.) with AH duration 0,5-43 years (average - 17,9 years). Antihypertensive effect of Amlorus (Synthesis, Russia) and Norvasc (Pfizer, USA) was evaluated in the study. Blood pressure (BP), amlodipine plasma levels (by liquid chromatography with mass spectrometry) and side effects were registered before and after 2, 4 and 6 weeks of therapy. Hydrochlorothiazide 25 mg/d was added if the monotherapy with amlodipine10 mg/d had not been efficient. Therapy with the second studied amlodipine followed the therapy with the first drug. Results. Both drugs provided similar plasma amlodipine concentrations with significant BP reduction. 96,6 % and 90 % of patients reached BP target level (<140/90 mm Hg) after 6 weeks of Amlorus and Norvasc therapy, respectively. Hydrochlorothiazide was needed in 23,3 % and 26,7 % of patients taking Amlorus and Norvasc, respectively. Cost of Amlorus therapy per patient was 221 rbl/month in comparison with cost of 727 rbl/month for Norvasc therapy. Conclusion. Generic Amlorus showed clinical and pharmacokinetic equivalency with an original amlodipine Norvasc and lower cost of therapy.

An article gives in a comprehensive manner the main idea of pharmacokinetics, as the science about rules of substances behavior in the internal environment of the organism, as well as of main parameters of pharmacokinetic researches. The article provides vivid and very persuasive examples of high practical importance of this science both for creating new medical forms of drugs and for choosing the optimal of therapy regime. Rational Pharmacother. Cardiol. 2005; 2: 43-47.