AIMTo study the pharmacokinetics of m-nifedipine (m-Nif) in Beagle dogs.

METHODSThe Beagle dogs were divided into two groups. m-Nif was intravenously administered to the Beagle dogs in group 1 at the dose of 0. 288 mg x kg(-1), and it was orally administered to the Beagle dogs in group 2, 3 and 4 at the dose of 1.152, 3.456 and 10.370 mg x kg(-1), respectively. m-Nif in plasma was detected by reversed phase high performance liquid chromatography. The pharmacokinetic parameters were calculated by 3P97 software.

RESULTSWhen m-Nif was intravenously administered, the plasma concentration-time curve was fit to a two-compartment model and T1/2beta was 117 min. When m-Nif was orally administered, the plasma concentration-time curve was fit to a one-compartment model. T1/2 (Ke) and Cmax were 147 min and 20 microg x L(-1); at the low dose of 1.152 mg x kg(-1). T1/2 (Ke) was 122 min and Cmax was 36 microg x L(-1) at the middle dose of 3.456 mg x kg(-1). T1/2 (Ke) was 144 min and Cmax was 69 microg x L(-1) at the high dose of 10.37 mg x kg(-1), respectively.

CONCLUSIONIt was showed that the speed of elimination of m-Nif was high in Beagle dogs. The absolute bioavailability of m-Nif given orally was very low.

Administration, Oral ; Animals ; Area Under Curve ; Biological Availability ; Calcium Channel Blockers ; administration & dosage ; pharmacokinetics ; Dogs ; Injections, Intravenous ; Isomerism ; Nifedipine ; administration & dosage ; pharmacokinetics

AIMTo develop a novel pulsatile drug delivery system of which the lag-time is controlled by an erodible plug (EP) and evaluate its release characteristics in vitro.

METHODSThe impermeable capsule body was prepared by fulfilling method and the drug tablet and the erodible plug were made by wet granulating compression. Tetramethylpyrazine phosphate (TMPP) pulsincap capsule was prepared by sealing the drug tablet and fillers inside the impermeable capsule body with the EP. The influence factors on the lag-time such as the EP pharmaceutical properties and the dissolution condition were investigated by dissolution testing.

RESULTSBoth the composition and the weight of EP influenced the lag-time of the tetramethylpyrazine phosphate pulsincap capsule significantly. The lag-time prior to the drug release was enhanced when the content of gel-forming excipient (hydroxypropylmethylcellulose, HPMC) in the EP or the weight of EP was increased. The hardness of EP showed minor influence on the lag-time. In addition, the lag-time was shortened when the paddle speed was higher, while the pH value of the dissolution medium exhibited no significant influence on it.

CONCLUSIONTo meet the chronotherapeutic requirements, a pulsatile drug delivery system with a suitable lag-time can be achieved by adjusting the composition and the EP weight.

Calcium Channel Blockers ; administration & dosage ; Capsules ; Delayed-Action Preparations ; Drug Delivery Systems ; Lactose ; analogs & derivatives ; Methylcellulose ; analogs & derivatives ; Oxazines ; Pyrazines ; administration & dosage ; Technology, Pharmaceutical

AIMTo study unitary-core osmotic pump tablet for delivering water-insoluble drug for 24 hours.

METHODSUnitary-core osmotic pump tablet was prepared using nifedipine as the model drug. The effects of various core formulation variables on drug release were studied.

RESULTSPolyethylene oxide and potassium chloride have comparable positive effects on drug release, whereas, nifedipine has markedly negative effect on drug release.

CONCLUSIONUnitary-core osmotic pump tablet is very easy in preparation and it can deliver water-insoluble drug in substantially constant rate for 24 hours.

Calcium Channel Blockers ; administration & dosage ; chemistry ; Delayed-Action Preparations ; Drug Delivery Systems ; Nifedipine ; administration & dosage ; chemistry ; Osmosis ; Polyethylene Glycols ; pharmacology ; Potassium Chloride ; pharmacology ; Solubility ; Tablets ; Technology, Pharmaceutical ; methods

The aim of this study was to evaluate the effects of fimasartan/amlodipine fixed-dosed combination (F/A) on left ventricle (LV) systolic function and infarct size in the rat myocardial infarction (MI) model. We induced MI in 20 rats by ligation of the left anterior descending coronary artery and they were divided into two groups [MI group (n=10) vs. MI+F/A 10 mg/kg group (n=10)]. F/A was administered for 28 days between day-7 and day-35 in the MI+F/A group and echocardiography was performed at day-7 and at day-35 after the induction of MI. Picrosirius red staining was performed to confirm the fibrotic tissue and infarct size was measured using image analysis program for Image J. At the 35-day follow-up, the LV ejection fraction (EF) was significantly higher (38.10±3.92% vs. 29.86±4.56%, p<0.001) and delta (day-35 minus day-7) EF was significantly higher (0.14±2.66% vs. −8.53±2.66%. p<0.001) in the MI+F/A group than the MI group. Systolic blood pressure was significantly lower in the MI+F/A group than the MI group (103.23±13.35 mmHg vs. 123.43±14.82 mmHg, p<0.01). The MI+F/A group had a smaller infarct size (26.84±5.31% vs. 36.79±3.10%, p<0.01) than the MI group at the 35-day follow-up. Oral administration of F/A 10 mg/kg could improve LV systolic function and reduce infarct size in a rat MI model.
Administration, Oral ; Angiotensin Receptor Antagonists ; Animals ; Blood Pressure ; Calcium Channel Blockers ; Coronary Vessels ; Echocardiography ; Follow-Up Studies ; Heart Ventricles ; Ligation ; Myocardial Infarction ; Rats ; Ventricular Remodeling

AIMTo prepare verapamil hydrochloride controlled-onset extended-release pellets (VH-COERP) and study its release behavior in vitro. To compare the pharmacokinetic characteristics and bioavailability in six Beagle dogs after oral administration of VH-COERP and verapamil hydrochloride delayed-release pellets (VH-DRP) as reference.

METHODSThe core of VH-COERP were prepared in the fluidized bed (mini-glatt) by spraying water solution containing drugs onto sucrose-starch pellets with hydroroxy propyl methyl cellulose (HPMC) as the inner coating swelling layer and ethylcellulouse aqueous dispersion as the outer coating controlled layer. Through modifying the coating level of inner and outer layer, the VH-COERP with the optimized cumulative release profile was obtained. The concentration of VH in plasma of six dogs and its pharmacokinetic behaviors after oral administration of VH-COERP and VH-DRP at different times were studied by RP-HPLC. The pharmacokinetic parameters were computed by software program 3P97.

RESULTSThe lag time, the release behavior and the amount of VH from VH-COERP within 24 hours were not influenced by the pH of dissolution medium and post-process, but obviously influenced by the different kinds of added material in swelling layer and the coating level of the inner swelling layer and the outer controlled layer. In vitro the lag time of release profile of VH from VH-COERP was 5 h and then VH was extended release from VH-COERP in the following time. Compared with the VH-DRP, VH-COERP in vivo has an obviously lag time (4 h) , Tmax was also delayed (8 h) and the relative bioavailability was (94.56 +/- 7.64)%.

CONCLUSIONThe release profile of VH from VH-COERP was shown to be extended-release after an conspicuous lag time in vitro and in vivo. So the drug can be taken by the patient before bed time and begin to work at the morning.

Administration, Oral ; Animals ; Biological Availability ; Calcium Channel Blockers ; administration & dosage ; pharmacokinetics ; Cellulose ; analogs & derivatives ; chemistry ; Delayed-Action Preparations ; Dogs ; Drug Stability ; Hypromellose Derivatives ; Methylcellulose ; analogs & derivatives ; chemistry ; Microscopy, Electron, Scanning ; Verapamil ; administration & dosage ; chemistry ; pharmacokinetics

OBJECTIVETo study the effects of total flavone of Abelmoschl Manihot L. Medic (TFA) on the function of platelets and to explore its mechanism.

METHODSRat models of artery-veins bypassing thrombus formation were used. The platelets of rabbits were collected. Platelet aggregation was induced by collagen and intracellular calcium ion concentration ([Ca(2+)]i) was assayed by Fura-2 method.

RESULTSTFA (25, 50, 100 mg/kg) significantly and dose-dependently reduced the weight of thrombus. TFA (0.025, 0.05, 0.1 mg/ml) possessed dose-dependant inhibitory effects on rabbits' platelet aggregation induced by collagen. TFA significantly reduced the resting and CaCl(2)-induced increase of free intracellular calcium concentration ([Ca(2+)]i) in rabbit platelet in vitro.

CONCLUSIONTFA has an antiplatelet effect via the inhibition on the influx of Ca(2+).

Animals ; Blood Platelets ; drug effects ; Calcium ; blood ; Calcium Channel Blockers ; administration & dosage ; pharmacology ; Calcium Chloride ; pharmacology ; Carotid Artery Thrombosis ; blood ; etiology ; Collagen ; pharmacology ; Dose-Response Relationship, Drug ; Drugs, Chinese Herbal ; administration & dosage ; pharmacology ; Flavones ; administration & dosage ; pharmacology ; Glycosides ; administration & dosage ; pharmacology ; Intracellular Membranes ; metabolism ; Osmolar Concentration ; Platelet Aggregation ; drug effects ; Platelet Aggregation Inhibitors ; administration & dosage ; pharmacology ; Platelet Function Tests ; Rabbits ; blood ; Rats ; Rats, Wistar

This study aims to save cost of sampling for estimating the area under the amlodipine plasma concentration versus time curve in 24 hours (AUC(0-24 h)). Limited sampling strategy (LSS) models was developed and validated by mutiple regression model within 4 or fewer amlodipine concentration values. Absolute prediction error (APE), root of mean square error (RMSE) and visual predict check were used as criterion. The results of Jackknife validation showed that fifteen (9.4%) of the 160 LSS based on regression analysis were not within an APE of 15% by using one concentration-time point. 156 (97.5%), 159 (99.4%) and 160 (100%) of the 160 LSS model were capable of predicting within an APE 15% by using 2, 3, 4 points, separately. Limited sampling strategies have been developed and validated for estimating AUC(0-24 h) of amlodipine. The present study indicated that the implemention of both 5 mg and 10 mg dosage could enable accurate predictions of AUC(0-24 h) by the same LSS model. This study shows that 12, 4, 24, 2 h after administration are key sampling time points. The combination of (12, 4), (12, 4, 24) or (12, 4, 24, 2 h) might be chosen as sampling hours for predicting AUC(0-24 h) in practical application according to requirement.
Administration, Oral ; Adult ; Amlodipine ; administration & dosage ; blood ; pharmacokinetics ; Antihypertensive Agents ; administration & dosage ; blood ; pharmacokinetics ; Area Under Curve ; Asian Continental Ancestry Group ; Calcium Channel Blockers ; administration & dosage ; blood ; pharmacokinetics ; Humans ; Male ; Models, Biological ; Regression Analysis ; Sample Size ; Vasodilator Agents ; administration & dosage ; blood ; pharmacokinetics ; Young Adult

AIMTo investigate the possible effect of tetramethylpyrazine (TMP), an active ingredient of a commonly used Chinese herb, on the pharmacokinetics of cyclosporine A (CsA) by intragastric administration in rats.

METHODSForty male Sprague-Dawley rats were equally divided into four groups by randomized block design according to weight. On the first day, after each fasting rat was intragastrically administered CsA (10 mg x kg(-1)), blood samples (0.2 - 0.25 mL) were collected from the tail vein at 0, 1, 2, 3, 4, 6, 8, 12, 24, 36 and 48 h. From day 4 to day 8, each group began to undergo different pretreatments with intragastric administration of water, verapamil (Ver), low and high dose TMP, separately. On day 9, each group intragastrically co-administered CsA (10 mg x kg(-1)) and different pretreatment compounds mentioned above, then blood samples were collected according to the schedule of the first day. The whole blood concentration of CsA was determined by HPLC. Main pharmacokinetic parameters were calculated and compared by statistic analysis.

RESULTSIn the group of water pretreated and co-administrated with CsA, no significantly different pharmacokinetic parameters of CsA were found. After Ver pretreatment and co-administration with CsA, AUC(0-48 h) and C(max) were increased significantly (P < 0.01 and P < 0.05); T(1/2) beta and CL were markedly prolonged and decreased (P < 0.05); T(max) and V were not apparently influenced. After low dose TMP pretreatment and co-administration with CsA, there was no significant difference in the pharmacokinetic parameters of CsA, in spite of the increasing trends of AUC(0-48 h) and C(max). After high dose TMP pretreatment and co-administration with CsA, AUC(0-48 h) and C(max) of CsA were increased significantly (P < 0.01), but there was no significant change in other parameters.

CONCLUSIONIt was indicated that the high dose of TMP could apparently increase the intragastric absorption extent of CsA, while almost had no effect on its elimination process.

Administration, Oral ; Animals ; Area Under Curve ; Biological Availability ; Calcium Channel Blockers ; pharmacology ; Cyclosporine ; administration & dosage ; blood ; pharmacokinetics ; Dose-Response Relationship, Drug ; Drug Administration Routes ; Immunosuppressive Agents ; administration & dosage ; blood ; pharmacokinetics ; Ligusticum ; chemistry ; Male ; Plants, Medicinal ; chemistry ; Pyrazines ; administration & dosage ; isolation & purification ; pharmacology ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Stomach ; Verapamil ; pharmacology

BACKGROUNDThe clinical significance of acute vasoreactivity testing (AVT) in patients with chronic thromboembolic pulmonary hypertension (CTEPH) remains unclear. We analyzed changes in hemodynamics and oxygenation dynamics indices after AVT in patients with CTEPH using patients with pulmonary arterial hypertension (PAH) as controls.

METHODSWe analyzed retrospectively the results of AVT in 80 patients with PAH and 175 patients with CTEPH registered in the research database of Beijing Chao-Yang Hospital between October 2005 and August 2014. Demographic variables, cardiopulmonary indicators, and laboratory findings were compared in these two subgroups. A long-term follow-up was conducted in patients with CTEPH. Between-group comparisons were performed using the independent-sample t-test or the rank sum test, within-group comparisons were conducted using the paired t-test or the Wilcoxon signed-rank test, and count data were analyzed using the Chi-squared test. Survival was estimated using the Kaplan-Meier method and log-rank test.

RESULTSThe rates of positive response to AVT were similar in the CTEPH (25/175, 14.3%) and PAH (9/80, 11.3%) groups (P > 0.05). Factors significantly associated a positive response to AVT in the CTEPH group were level of N-terminal pro-brain natriuretic peptide (≤1131.000 ng/L), mean pulmonary arterial pressure (mPAP, ≤44.500 mmHg), pulmonary vascular resistance (PVR, ≤846.500 dyn·s-1·m-5), cardiac output (CO, ≥3.475 L/min), and mixed venous oxygen partial pressure (PvO2, ≥35.150 mmHg). Inhalation of iloprost resulted in similar changes in mean blood pressure, mPAP, PVR, systemic vascular resistance, CO, arterial oxygen saturation (SaO2), mixed venous oxygen saturation, partial pressure of oxygen in arterial blood (PaO2), PvO2, and intrapulmonary shunt (Qs/Qt) in the PAH and CTEPH groups (all P > 0.05). The survival time in patients with CTEPH with a negative response to AVT was somewhat shorter than that in AVT-responders although the difference was not statistically significant (χ2 =3.613, P = 0.057). The survival time of patients with CTEPH who received calcium channel blockers (CCBs) was longer than that in the group with only basic treatment and not shorter than that of patients who receiving targeted drugs or underwent pulmonary endarterectomy (PEA) although there was no significant difference between the four different treatment regimens (χ2 =3.069, P = 0.381).

CONCLUSIONSThe rates of positive response to AVT were similar in the CTEPH and PAH groups, and iloprost inhalation induced similar changes in hemodynamics and oxygenation dynamics indices. A positive response to AVT in the CTEPH group was significantly correlated with milder disease and better survival. Patients with CTEPH who cannot undergo PEA or receive targeted therapy but have a positive response to AVT might benefit from CCB treatment.

Administration, Inhalation ; Adult ; Aged ; Arterial Pressure ; drug effects ; Atrial Natriuretic Factor ; metabolism ; Calcium Channel Blockers ; administration & dosage ; therapeutic use ; Endarterectomy ; Familial Primary Pulmonary Hypertension ; drug therapy ; physiopathology ; Female ; Hemodynamics ; drug effects ; Humans ; Hypertension, Pulmonary ; drug therapy ; physiopathology ; Iloprost ; administration & dosage ; therapeutic use ; Male ; Middle Aged ; Protein Precursors ; metabolism ; Retrospective Studies ; Software ; Vasodilator Agents ; administration & dosage ; therapeutic use

OBJECTIVETo evaluate the efficacy and tolerability of the fixed combination of amlodipine 5 mg/benazepril 10 mg once-daily therapy, compared with benazepril, 10 mg, monotherapy in patients with mild and moderate hypertension, and to evaluate the 24 h antihypertensive efficacy and the duration of action by ambulatory blood pressure monitoring.

METHODSIn a multicenter, randomized, double-blind, parallel controlled trial, 356 cases of hypertensive patients after 2 weeks wash-out, and then given 4 weeks of benazepril 10 mg monotherapy, 220 patients with mean seated diastolic blood pressure (SeDBP) remained ≥ 90 mm Hg (1 mm Hg = 0.133 kPa) were randomly divided into benazepril 10 mg/amlodipine 5 mg (BZ10/AML5) fixed-dose combination therapy group (once a day, n = 113), and benazepril monotherapy group (daily 20 mg, n = 107). In the two groups the patients with SeDBP ≥ 90 mm Hg were doubled the dosage of the initial regimen at the end of 4-week treatment for additional 4 weeks, and the patients with SeDBP < 90 mm Hg remained the initial regimen for additional 4 weeks. The primary endpoint was to evaluate the improvement of SeDBP at the end of 8-week treatment. There were 74 patients (the combination therapy group n = 38, monotherapy therapy group n = 36) completed the 24 h ambulatory blood pressure monitoring which was included in the final efficacy analysis.

RESULTSThe randomized, double-blind treatment for 8 weeks, the mean value of SeDBP reduction, the reaching target blood pressure rate and total successful response rate to the treatment (a SeDBP < 90 mm Hg or a decrease of 10 mm Hg or more from baseline) were (11.7 ± 6.8) mm Hg, 65.7% and 88.5% in the combination therapy group, respectively, and were (7.7 ± 6.9) mm Hg, 35.5% and 65.5% in the monotherapy group, respectively. There were statistically significant difference between the combination therapy and the monotherapy groups in all the 3 indexs (P < 0.001). The fixed combination significantly reduced systolic blood pressure (SBP) and diastolic blood pressure (DBP) values throughout the 24 h. The trough to peak ratios of DBP/SBP in the fixed compound of benazepril/amlodipine (10 mg/5 mg) and benazepril (20 mg) alone were 83.1%/76.0% and 85.8%/79.5%, respectively. Adverse events rates were 16.8% in the combination therapy group and 35.5% in the monotherapy group (P < 0.001).

CONCLUSIONSThe combination therapy with benazepril/amlodipine was superior to benazepril monotherapy and was well tolerated in patients with essential hypertension and allowing a satisfactory BP control for 24 hours.

Adult ; Amlodipine ; adverse effects ; therapeutic use ; Angiotensin-Converting Enzyme Inhibitors ; administration & dosage ; therapeutic use ; Antihypertensive Agents ; administration & dosage ; therapeutic use ; Benzazepines ; administration & dosage ; therapeutic use ; Calcium Channel Blockers ; adverse effects ; therapeutic use ; Double-Blind Method ; Drug Combinations ; Female ; Humans ; Hypertension ; drug therapy ; Male ; Middle Aged