1
|
Regidor PA, Richter WH, Koytchev R, Kirkov V, Colli E. Evaluation of the food effect on a drospirenone only contraceptive containing 4 mg administered with and without high-fat breakfast in a randomised trial. BMC Womens Health 2022; 22:381. [PMID: 36123682 PMCID: PMC9484173 DOI: 10.1186/s12905-022-01960-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 09/02/2022] [Indexed: 12/04/2022] Open
Abstract
Background The objective of the present trial was to assess the difference in pharmacokinetics (PK) of an oral test preparation containing 4 mg drospirenone (DRSP) under fasting conditions compared to PK upon food intake after single dose administration.
Methods Open label, single centre, two-treatment, two-sequence, crossover study in 24 healthy female volunteers, with duration of 1 day per sequence and with a real wash-out period of 14 days to investigate the relative bioavailability of DRSP with both forms of administration. The 90% confidence intervals (CI) were calculated for the intra-individual ratio (test with food vs. without food) of the PK endpoints Area under the curve; 0–72 h [AUC(0-72 h)] and maximal plasma concentration [Cmax] of DRSP.
Results The 90% CI calculated by analysis of variance using logistic transformation (ANOVA-log) for the endpoint, intra-individual ratio (Test ‘A’ = with food intake) vs. Test ‘B’ = without food intake) of AUC(0-72 h) of drospirenone was between 104.72 and 111.36%. The 90% CI calculated by means of ANOVA- log for the endpoint intra-individual ratio (Test ‘A’ vs. Test ‘B’) of Cmax of DRSP was between 118.58 and 141.10%. The mean relative bioavailability of the test with food ‘A’ compared to the Test without food ‘B’ after single dose administration based on the endpoints AUC(0-72 h) was 107.99%; for the endpoint Cmax it was 129.35%. Conclusions The rate of absorption, based on the endpoint Cmax of DRSP was increased by about 30% under fed conditions. With respect to consumer habits, this may represent a relevant benefit for contraceptive safety, as the time span between food consumption and pill intake does not play a role. Implications Our results suggest that the food intake has no impact on the absorption of 4 mg DRSP in the management of contraception. This increases the contraceptive efficacy as no interference with food is expected when consuming the oral formulation under real life conditions. Trail registration: Trial registration number: EudraCT-No: 2012–004,309-28.
Collapse
|
2
|
Landzhov B, Gaydarski L, Tubbs RS, Kirkov V, Georgiev GP. A unique variation of a four-bellied digastric muscle named "real quadrigastric muscle": a case report and literature review. Folia Morphol (Warsz) 2022; 82:735-739. [PMID: 35818809 DOI: 10.5603/fm.a2022.0063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 06/13/2022] [Indexed: 11/25/2022]
Abstract
From a topographical standpoint, the digastric muscle is key to the formation of several triangles of the neck, which are of the utmost clinical significance. Herein, we present a previously unrecognised variation of the digastric muscle: a quadrigastric muscle with two accessory bellies originating from the body and angle of the mandible and inserting to the intermediate tendon. Three new triangles are demarcated between the four bellies of the aberrant muscle. Detailed knowledge of variations of the digastric muscle, changing the borders and relationships of the topographic triangles, is paramount for radiologists and surgeons operating on the anterior region of the neck.
Collapse
Affiliation(s)
- B Landzhov
- Department of Anatomy, Histology and Embryology, Medical University of Sofia, Bulgaria.
| | - L Gaydarski
- Department of Anatomy, Histology and Embryology, Medical University of Sofia, Bulgaria
| | - R S Tubbs
- Department of Neurology, Tulane University School of Medicine, New Orleans, Louisiana, United States
| | - V Kirkov
- Department of Health Policy and Management, Medical University of Sofia, Bulgaria
| | - G P Georgiev
- Department of Orthopaedics and Traumatology, University Hospital Queen Giovanna - ISUL, Medical University of Sofia, Bulgaria
| |
Collapse
|
3
|
Landzhov B, Gaydarski L, Angushev I, Tivcheva Y, Olewnik L, Krastev N, Kirkov V, Georgiev GP. Variations in the Origin of the Superior Laryngeal Artery and their Clinical Significance: A Case Report with a Proposal for a New Classification. INT J MORPHOL 2022. [DOI: 10.4067/s0717-95022022000300595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
4
|
Stanchev S, Stamenov N, Kirkov V, Dzhambazova E, Nikolov D, Paloff A. Differential collagen expression in kidney and heart during hypertension. ACTA ACUST UNITED AC 2020; 121:73-78. [PMID: 31950843 DOI: 10.4149/bll_2020_011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
AIM The aim of the present study was to investigate the immunohistochemical expression of selected collagen types, namely collagen types I and V and procollagen type III in the renal parenchyma and interstitium and in the myocardium of spontaneously hypertensive rats. MATERIAL AND METHODS For the present study, we used two age groups of 6- and 12-month-old spontaneously hypertensive rats. An immunohistochemical analysis was conducted with monoclonal antibodies against collagen types I and V and procollagen type III. A semi-quantitative analysis of immunostaining intensity was conducted with the Image J software. RESULTS In the kidney, all three molecules showed higher expression at the age of 12 months, which was particularly notable for procollagen type III and collagen type V, which stained as highly-positive. In the myocardium, the immunoreactivity of collagen types I and V was stronger in 12-month-old animals, while that of procollagen type III did not change substantially. CONCLUSION The present study suggests a role of collagen types III and V in hypertensive kidney disease, while also establishing the role of increased expression of collagen types I and V in adverse myocardial remodeling (Tab. 1, Fig. 2, Ref. 48).
Collapse
|
5
|
Richter WH, Koytchev R, Kirkov V, Merki G, Colli E, Regidor PA. Comparative pharmacokinetic estimates of drospirenone alone and in combination with ethinyl estradiol after single and repeated oral administration in healthy females. Contraception 2019; 101:137-143. [PMID: 31758920 DOI: 10.1016/j.contraception.2019.10.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Revised: 10/14/2019] [Accepted: 10/17/2019] [Indexed: 10/25/2022]
Abstract
OBJECTIVE To determine the pharmacokinetics (PK) of drospirenone (DRSP), alone versus in combination with ethinyl estradiol (EE), after single and repeated administration. STUDY DESIGN We conducted a single-centre, open-label, crossover, 2-treatment, 2-period, 2-sequence study in which non-micronized DRSP 4 mg or a combination of DRSP 3 mg and EE 0.02 mg were administered to healthy female subjects on day 1 to obtain a single-dose kinetic profile, and from day 4 to day 15 to obtain a repeated-dose kinetic profile. The maximum observed concentration (Cmax) and area under the concentration/time curve (AUC) were determined in a model-independent way using non dose corrected data. Statistical analysis was based on a parametric method (ANOVA-log). RESULTS A total of 24 healthy female subjects were randomized 1:1 into the study. The mean relative, non-dose-corrected PK estimates after single-dose administration for the endpoints AUC(0-72h), AUC(0-24h) and Cmax were 543.5 ng*h/mL, 296.1 ng*h/mL and 27.3 ng/mL for DRSP alone, and 442.0 ng*h/mL, 264.7 ng*h/mL and 37.5 ng/mL for the DRSP/EE combination; p < 0.001. The mean relative, non-dose-corrected PK estimates after repeated dose administration for the endpoints AUC(0-72h), AUC(0-24h) and Cmax were 1066.8 ng*h/ml, 570.2 ng*h/mL and 41.0 ng/mL for DRSP alone, and 1394.5 ng*h/mL, 732.8 ng*h/mL and 61.4 ng/mL for the DRSP/EE combination; p < 0.001. CONCLUSIONS DRSP alone exhibits a lower accumulation ratio than together with EE. The extent of systemic exposure at steady-state is about 32% less with the new formulation (AUC(0-24h), steady-state geometric mean ratio: 77.8%; 90% confidence interval: 74.6%-81.1%). This PK profile may be caused by EE. IMPLICATIONS Our results suggest that metabolic pathways of DRSP can be inhibited by EE resulting in higher DRSP plasma concentrations in DRSP/EE formulations than in a DRSP-alone formulation. The enzymes CYP3A4 and SULT1A1 may play a role. Additional drug-drug-interaction studies are needed to better understand these metabolic pathways and their future clinical implications.
Collapse
Affiliation(s)
| | | | | | - G Merki
- Klinik für Reproduktions-Endokrinologie, Universitäts Spital Zürich, Switzerland.
| | - E Colli
- Exeltis Healthcare, Germany.
| | | |
Collapse
|
6
|
Perry J, Trautman B, Takher-Smith J, Kramer S, Kane K, Silverman M, Tan L, Haughie S, Richter W, Kirkov V, Arsova S, Ward J, Hava DL. Particle size and gastrointestinal absorption influence tiotropium pharmacokinetics: a pilot bioequivalence study of PUR0200 and Spiriva HandiHaler. Br J Clin Pharmacol 2019; 85:580-589. [PMID: 30521129 DOI: 10.1111/bcp.13831] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 11/16/2018] [Accepted: 11/29/2018] [Indexed: 12/23/2022] Open
Abstract
AIMS Plasma pharmacokinetics permit the assessment of efficacy and safety of inhaled drugs, and possibly their bioequivalence to other inhaled products. Correlating drug product attributes to lung deposited dose is important to achieving equivalence. PUR0200 is a spray-dried formulation of tiotropium that enables more efficient lung delivery than Spiriva® HandiHaler® (HH). The ratio of tiotropium lung-to-oral deposition in PUR0200 was varied to investigate the impact of particle size on tiotropium pharmacokinetics, and the contribution of oral absorption to tiotropium exposure was assessed using charcoal block. METHODS A seven-period, single-dose, crossover study was performed in healthy subjects. PUR0200 formulations differing in dose and aerodynamic particle size were administered in five periods and Spiriva HH in two periods. In one period, Spiriva HH gastrointestinal absorption was blocked with oral charcoal. Tiotropium plasma concentrations were assessed over 8 h after inhalation. RESULTS PUR0200 pharmacokinetics were influenced by aerodynamic particle size and the ratio of lung-to-oral deposition, with impactor sized mass (ISM) correlating most strongly with exposure. Formulation PUR0217a (3 μg tiotropium) lung deposition was similar to Spiriva HH (18 μg) with and without charcoal block, but total PUR0200 exposure was lower without charcoal. The Cmax and AUC0-0.5h of Spiriva HH with and without charcoal block were bioequivalent; however, Spiriva HH AUC0-8h was lower when gastrointestinal absorption was inhibited with oral charcoal administration. CONCLUSIONS Pharmacokinetic bioequivalence indicative of lung deposition and efficacy can be achieved by matching the reference product ISM. Due to reduced oral deposition and more efficient lung delivery, PUR0200 results in a lower AUC0-t than Spiriva HH due to reduced absorption of drug from the gastrointestinal tract.
Collapse
Affiliation(s)
- Jason Perry
- Pulmatrix Inc, 99 Hayden Ave, Suite 390, Lexington, MA, 02421, USA
| | - Brian Trautman
- Pulmatrix Inc, 99 Hayden Ave, Suite 390, Lexington, MA, 02421, USA
| | | | - Steve Kramer
- Pulmatrix Inc, 99 Hayden Ave, Suite 390, Lexington, MA, 02421, USA
| | - Katie Kane
- Pulmatrix Inc, 99 Hayden Ave, Suite 390, Lexington, MA, 02421, USA
| | | | - Lisa Tan
- Pulmatrix Inc, 99 Hayden Ave, Suite 390, Lexington, MA, 02421, USA
| | - Scott Haughie
- Mylan Global Respiratory Group, Discovery Park, Sandwich, UK
| | - Wolfram Richter
- Cooperative Clinical Drug Research and Development, Hoppegarten, Germany
| | - Valentin Kirkov
- Clinic for Internal Diseases, MHAT Tokuda Hospital, Sofia, Bulgaria
| | - Sacha Arsova
- Cooperative Clinical Drug Research and Development, Hoppegarten, Germany
| | - Jonathan Ward
- Mylan Global Respiratory Group, Discovery Park, Sandwich, UK
| | - David L Hava
- Pulmatrix Inc, 99 Hayden Ave, Suite 390, Lexington, MA, 02421, USA
| |
Collapse
|
7
|
Algorta J, Andrade L, Medina M, Kirkov V, Arsova S, Li F, Chi J. Pharmacokinetic Bioequivalence of Two Inhaled Tiotropium Bromide Formulations in Healthy Volunteers. Clin Drug Investig 2017; 36:753-762. [PMID: 27470430 PMCID: PMC4987402 DOI: 10.1007/s40261-016-0441-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Background and Objective A novel tiotropium bromide monodose capsule dry powder inhaler (DPI) formulation and device have been developed. The formulation was based on a spray-dried matrix that enhances the aerosolizaton properties, allowing a less active tiotropium metered dose (13 µg/capsule) while maintaining the same delivered dose (10 µg/actuation). This study describes the pharmacokinetic bioequivalence to the reference product. Methods This randomized, two-stage, crossover, semi-replicate (three-way) study was performed in healthy volunteers. In each study period, subjects received a single dose of two capsules (20 μg delivered dose) of the study medication, separated by a 14-day washout period: tiotropium 10 μg delivered dose (Laboratorios Liconsa, Spain) and Spiriva HandiHaler® (Boehringer Ingelheim Pharma GmbH & Co KG, Germany). Blood samples were obtained up to 48 h post-dose to evaluate the comparative bioavailability. Tiotropium was measured in plasma by means of dual stage liquid–liquid extraction followed by the two-dimensional ultra-high performance liquid chromatography sensitive sub-pg/mL bioanalytical method. The main pharmacokinetic parameters were maximum plasma concentration (Cmax), area under the concentration–time curve (AUC) from time zero hours to the last observed concentration at time t (AUCt), and AUC from time zero hours to 30 min (AUC0.5). Bioequivalence was accepted if the 90.20 % confidence interval (CI) for the ratio test/reference of the primary pharmacokinetic parameters lay within the acceptance range of 80–125 %. Safety assessment was a secondary endpoint. Results A total of 30 subjects were randomized and bioequivalence was demonstrated for all primary pharmacokinetic parameters: Cmax (CI 87.26–106.60 %), AUCt (CI 101.33–111.64 %), and AUC0.5 (CI 97.95–113.49 %). Both study treatments were well tolerated (four non-serious adverse events [AEs] were reported in four subjects: one AE before any product administration, two AEs after test product administration; and one AE after reference product administration). Conclusions Both products containing tiotropium 10 µg delivered-dose DPI were bioequivalent and showed good tolerability and a similar safety profile.
Collapse
Affiliation(s)
- Jaime Algorta
- Laboratorios Liconsa, Avda. Miralcampo 7, 19200, Azuqueca de Henares, Spain.
| | - Laura Andrade
- Laboratorios Liconsa, Avda. Miralcampo 7, 19200, Azuqueca de Henares, Spain
| | - Marta Medina
- Laboratorios Liconsa, Avda. Miralcampo 7, 19200, Azuqueca de Henares, Spain
| | - Valentin Kirkov
- Clinic for Internal Diseases, MHAT Tokuda Hospital Sofia EAD, Sofia, Bulgaria
| | - Sacha Arsova
- Cooperative Clinical Drug Research and Development, Hoppegarten, Germany
| | - Fumin Li
- PPD Laboratories, Middleton, WI, USA
| | | |
Collapse
|
8
|
Kirkov V, Dimitrova V, Siebert-Weigel M, Wolf-Pflugmann M, Koytchev R, Richter W, Bronn A, Arsova S, Kromminga A. Evaluation of the Pharmacokinetics of Two Recombinant Human Erythropoietin Preparations: Epoetin Zeta and Epoetin Alfa. ACTA ACUST UNITED AC 2011; 58:220-4. [DOI: 10.1055/s-0031-1296498] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
| | | | | | | | - Rossen Koytchev
- Cooperative Clinical Drug Research and Development (CCDRD) AG
| | - Wolfram Richter
- Cooperative Clinical Drug Research and Development (CCDRD) AG
| | - Angelika Bronn
- Cooperative Clinical Drug Research and Development (CCDRD) AG
| | - Sacha Arsova
- Cooperative Clinical Drug Research and Development (CCDRD) AG
| | | |
Collapse
|
9
|
Koytchev R, Richter W, Erkent U, Kirkov V, Dimitrova V, Nern A, Kunter U. Influence of acarbose on blood glucose and breath hydrogen after carbohydrate load with sucrose or starch. ACTA ACUST UNITED AC 2010; 59:557-63. [PMID: 20066964 DOI: 10.1055/s-0031-1296444] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
A monocentric, open, randomised, single-dose, six-period crossover trial was carried out in healthy volunteers under fasting conditions to establish the most appropriate study design for a pivotal bioequivalence trial with acarbose (CAS 56180-94-0) regarding a) dosage of the drug, b) type of carbohydrate load, c) type of primary endpoint, and d) sample size. 50 g sucrose or 50 g starch were used as carbohydrate load. Acarbose was administered in doses of 50 and 200 mg. Blood glucose and breath hydrogen were evaluated as endpoints. Both acarbose doses reduced the effect of carbohydrate load. Blood glucose: no statistically significant difference could be noted between the overall effect of 50 mg and that of 200 mg acarbose irrespective of the type of carbohydrate load. Breath hydrogen: an influence could be shown only for sucrose as carbohydrate load. Practically no effect was observed with starch. The overall increase of effect is by more than 200% with sucrose when the dose of acarbose increases from 50 to 200 mg. This difference between the effects of both doses of acarbose on breath hydrogen is statistically significant. For a pivotal trial, sucrose is the most appropriate type of carbohydrate load, baseline adjusted area under the breath hydrogen response is the most appropriate primary endpoint, and a dose of 100 mg acarbose is the most appropriate dosage. A total number of 100 subjects will be needed for proving pharmacodynamic equivalence between two acarbose products in a pivotal trial.
Collapse
Affiliation(s)
- Rossen Koytchev
- Cooperative Clinical Drug Research and Development AG, Neuenhagen, Germany.
| | | | | | | | | | | | | |
Collapse
|
10
|
Kirkov V, Dimitrova V, Siebert-Weigel M, Wolf-Pflugmann M, Koytchev R, Richter W, Bronn A, Arsova S, Kromminga A. Evaluation of the pharmacokinetics of two recombinant human erythropoietin preparations: epoetin zeta and epoetin alfa. 1st Communication: A monocentric, open, randomized, single dose, two-period crossover trial in healthy volunteers. Arzneimittelforschung 2008; 58:215-9. [PMID: 18589555 DOI: 10.1055/s-0031-1296497] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
The pharmacokinetic properties of a new recombinant erythropoietin preparation (epoetin zeta, CAS 604802-70-2) compared to a reference product (epoetin alfa, CAS 113427-24-0) were analyzed after a single intravenous bolus injection of 10,000 IU in a two-period crossover design in 24 healthy volunteers. Peripheral venous blood samples were obtained pre-dose, and 0:05, 0:20, 0:40, 1:00, 1:20, 1:40, 2:00, 3:00, 4:00, 6:00, 8:00, 12:00, 24:00, 36:00, 48:00, and 72:00 hours post dosing. Samples of 24 volunteers were analyzed by means of a specific immunoassay (ELISA). Three volunteers were excluded from statistical analysis due to a paravasal injection in one of both study periods with resulting low plasma levels of epoetin. Comparison of both preparations showed nearly identical pharmacokinetic properties after intravenous administration. The usual bioequivalence limits were fulfilled for all relevant pharmacokinetic parameters.
Collapse
|
11
|
Gatchev E, Thyroff-Friesinger U, Bakracheva N, Kirkov V, Koytchev R, van der Meer MJ. Analysis of pooled plasma samples as a predictor for proving bioequivalence of drugs with a long elimination half-life. The example of phenprocoumon. Arzneimittelforschung 2004; 54:685-9. [PMID: 15553109 DOI: 10.1055/s-0031-1297022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
The results of pooled plasma analysis in a bioequivalence trial provide information comparable with that of the mean concentration vs. time curves for each formulation. Although it seems feasible that pool plasma analysis will have similar or even greater advantages in cases of bioequivalence trials with a parallel-group design, no such data has been published in the literature probably due to the limited number of such trials. The present study was designed with the aim to investigate the prediction value of pool plasma analysis in a bioequivalence trial with phenprocoumon (CAS 435-972). The study was performed as a monocentric, randomized, open clinical trial in two parallel groups of healthy male volunteers (31 per group), all of which received a single oral dose of 3 mg phenprocoumon. Serial blood samples were drawn for the pharmacokinetic analysis pre-dose, and 0.33, 0.67, 1, 1.5, 2, 2.5, 3, 3.5, 4, 6, 12, 24, 48, 96, 144, 192, and 240 h after drug administration. Pool plasma was prepared for each sampling point and each formulation. Drug concentrations were measured by means of an HPLC method. A comparison between the pool plasma results and the results of individual analysis revealed a very good correspondence regarding the parameters AUC, Cmax and t(max). The present trial demonstrates that the method of time-wise pooling provides reliable information not only in cross-over trials but also in trials with parallel groups of volunteers.
Collapse
Affiliation(s)
- Emil Gatchev
- Department of Clinical Pharmacology and Therapeutics, Medical University of Sofia, Sofia (Bulgaria)
| | | | | | | | | | | |
Collapse
|
12
|
Koytchev R, Alken RG, Vlahov V, Kirkov V, Kaneva R, Thyroff-Friesinger U, Rehak E. Influence of the cytochrome P4502D6*4 allele on the pharmacokinetics of controlled-release metoprolol. Eur J Clin Pharmacol 1998; 54:469-74. [PMID: 9776437 DOI: 10.1007/s002280050495] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
AIM The aim of the present paper was to compare the pharmacokinetics of metoprolol in homozygous Caucasian volunteers for the wild-type CYP2D6 allele (CYP2D6*1/CYP2D6*1) and heterozygous (CYP2D6*1/CYP2D6*4) Caucasians. METHODS Thirty-six unrelated healthy male Caucasians were screened for two of the most frequently occurring mutant alleles (CYP2D6*3 and CYP2D6*4) using polymerase chain reaction (PCR). Twenty-four volunteers with a genotype suggesting a rapid hydroxylator phenotype were enrolled in a bioequivalence trial and each received in a randomized, cross-over fashion one of the three formulations compared. Each formulation contained 200 mg metoprolol tartrate/(tablet). In each of the three periods of the trial, one of the formulations was administered under fasting conditions in the morning on 4 consecutive days. Blood for quantification of metoprolol was drawn immediately before the last dose and in selected time intervals thereafter. A sensitive and specific high-performance liquid chromatography (HPLC) method with fluorescence detection was applied for the quantification of metoprolol. Pharmacokinetic parameters were determined for each subject and statistically compared in two groups of 16 homozygous (CYP2D6*1/CYP2D6*1) and six heterozygous (CYP2D6*1/CYP2D6*4) volunteers. RESULTS Significant differences between homozygous and heterozygous individuals were observed for all pharmacokinetic parameters. The AUC in the course of one those interval of 24 h (AUCtau), minium steady-state concentration (C(min)ss) and average steady-state concentration (C(av)ss) values for heterozygous individuals were more than twice those of individuals. Significantly higher values for C(max)ss, t1/2, half-value duration (HVD) and mean residence time (MRT) were also observed in heterozygous volunteers. The higher concentrations of metoprolol in heterozygous individuals also had pharmacodynamic consequences, namely, greater heart rate and blood pressure reduction.
Collapse
Affiliation(s)
- R Koytchev
- Co-operative Clinical Drug Research and Development, Berlin, Germany
| | | | | | | | | | | | | |
Collapse
|
13
|
Koytchev R, Alken RG, Vagaday M, Kunter U, Kirkov V. Differences in the bioavailability of dihydrotachysterol preparations. Eur J Clin Pharmacol 1994; 47:81-4. [PMID: 7988630 DOI: 10.1007/bf00193484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The bioavailability of four preparations containing dihydrotachysterol (DHT2) was tested in two separate trials with administration of single, oral doses of 1 mg per individual. The relative bioavailability of corresponding preparations (capsules vs capsules and oral solution vs oral solution) was tested in a randomised, cross-over pattern within the same group of volunteers. Two different groups of 24 healthy volunteers took part in each trial. Solution and capsule bioavailability was also compared inter-individually. A new sensitive HPLC-method (quantification limit 0.5 ng.ml-1) was used for the measurement of DHT2 concentration in serum. Three of the preparations tested had a similar bioavailability (mean AUC values of 195.5-223 ng.h.ml-1); the bioavailability of the fourth preparation (A.T.10 oral solution) was considerably lower (mean AUC value 111.5 ng.h.ml-1). The present dosage recommendations of all four preparations are identical. A new dosage recommendation is thus required for the oral solution with low bioavailability (A.T.10).
Collapse
Affiliation(s)
- R Koytchev
- Pharmacological Research Company Biopharm GmbH, Berlin, Germany
| | | | | | | | | |
Collapse
|
14
|
Koytchev R, Alken RG, Kirkov V, Neshev G, Vagaday M, Kunter U. [Absolute bioavailability of chlorpromazine, promazine and promethazine]. Arzneimittelforschung 1994; 44:121-5. [PMID: 8147942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The absolute bioavailability of the three phenothiazine neuroleptics, promazine (Sinophenin, CAS 58-40-2), chlorpromazine (Propaphenin, CAS 50-53-3) and promethazine (Prothazin, CAS 60-87-7) was tested in three single-dose cross-over studies. In each trial 12 to 14 healthy volunteers were enrolled. The single doses for promazine, promethazine and chlorpromazine were 100, 75 and 150 mg (orally) and 20, 50 and 50 mg (intravenously), resp. The serum concentrations of the three neuroleptics were measured by means of a selective HPLC-method. the distribution-free confidence intervals for the absolute bioavailability of the three phenothiazines were within 10.5 to 24.7% for chlorpromazine, 7.8 to 24.9% for promazine and 12.3 to 40% for promethazine. Promazine and chlorpromazine are pharmacokinetically very similar and differ substantially from promethazine.
Collapse
Affiliation(s)
- R Koytchev
- Lehrstuhl für Klinische Pharmakologie, Medizinische Akademie, Sofia, Bulgarien
| | | | | | | | | | | |
Collapse
|
15
|
Vlahov V, Kirkov V, Popov P, Gerova Z. Protective effect of rioprostil on indomethacin-induced lesions of gastric and duodenal mucosa in healthy volunteers. Scand J Gastroenterol Suppl 1989; 164:169-73. [PMID: 2510262 DOI: 10.3109/00365528909091207] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The protective effect of rioprostil against gastroduodenal mucosal lesions induced by indomethacin is investigated in a double-blind controlled trial on 36 healthy adult volunteers, divided into three groups. All the volunteers are treated with indomethacin, 50 mg t.d.s. during a period of 5 days. The first group is treated with placebo, the second with rioprostil, 300 micrograms, and the third with rioprostil, 600 micrograms. Endoscopies are performed before and after treatment. Blood samples for high performance liquid chromatography determination of indomethacin plasma concentrations are taken on the 6th day, before the last dose of indomethacin is administered, and 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 10, 12 and 24 h after the last dose of indomethacin. It is found that in both doses rioprostil exerts a protective effect against indomethacin-induced lesions, reducing the appearance rate of erosions from 67% to 17% statistically significant in the 600 micrograms group. The bioavailability of indomethacin in the three groups does not differ significantly.
Collapse
Affiliation(s)
- V Vlahov
- Institute of Pharmacology and Pharmacy, Medical Academy, Sofia, Bulgaria
| | | | | | | |
Collapse
|
16
|
Pernov K, Kirkov V, Spasowski N, Drjanovska T, Bobev G. [Use of the mustard test in examining workers exposed to ethylene]. Z Gesamte Hyg 1980; 26:19-20. [PMID: 7415326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
|
17
|
Nedelcheva K, Kirkov V, Khadzhieva I, Trendafilova R. [Study of catecholamine excretion in vibration disease]. Gig Tr Prof Zabol 1976:49-51. [PMID: 950169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
|