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Physiologically based pharmacokinetic (PBPK) modelling of tamsulosin related to CYP2D6*10 allele. Arch Pharm Res 2021; 44:1037-1049. [PMID: 34751931 DOI: 10.1007/s12272-021-01357-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Accepted: 11/03/2021] [Indexed: 12/13/2022]
Abstract
Tamsulosin, a selective [Formula: see text]-adrenoceptor blocker, is commonly used for alleviation of lower urinary tract symptoms related to benign prostatic hyperplasia. Tamsulosin is predominantly metabolized by CYP3A4 and CYP2D6 enzymes, and several studies reported the effects of CYP2D6 genetic polymorphism on the pharmacokinetics of tamsulosin. This study aims to develop and validate the physiologically based pharmacokinetic (PBPK) model of tamsulosin in CYP2D6*wt/*wt, CYP2D6*wt/*10, and CYP2D6*10/*10 genotypes, using Simcyp® simulator. Physicochemical, and formulation properties and data for absorption, distribution, metabolism and excretion were collected from previous publications, predicted in the simulator, or optimized in different CYP2D6 genotypes. The tamsulosin PBPK model in CYP2D6*wt/*wt and CYP2D6*wt/*10 genotypes were developed based on the clinical pharmacokinetic study where a single oral dose of 0.2 mg tamsulosin was administered to 25 healthy Korean male volunteers with CYP2D6*wt/*wt and CYP2D6*wt/*10 genotypes. A previous pharmacokinetic study was used to develop the model in CYP2D6*10/*10 genotype. The developed model was validated using other clinical pharmacokinetic studies not used in development. The predicted exposures via the PBPK model in CYP2D6*wt/*10 and CYP2D6*10/*10 genotype was 1.23- and 1.76-fold higher than CYP2D6*wt/*wt genotype, respectively. The simulation profiles were visually similar to the observed profiles, and fold errors of all development and validation datasets were included within the criteria. Therefore, the tamsulosin PBPK model in different CYP2D6 genotypes with regards to CYP2D6*10 alleles was appropriately established. Our model can contribute to the implementation of personalized pharmacotherapy of patients, appropriately predicting the pharmacokinetics of tamsulosin reflecting their demographic and CYP2D6 genotype characteristics without unnecessary drug exposure.
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Ogasawara K, Smith WB, Xu C, Yin J, Palmisano M, Krishna G. Pharmacokinetics and tolerability of fedratinib, an oral, selective Janus kinase 2 inhibitor, in subjects with renal or hepatic impairment. Cancer Chemother Pharmacol 2020; 85:1109-1117. [PMID: 32449142 DOI: 10.1007/s00280-020-04084-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 05/13/2020] [Indexed: 01/29/2023]
Abstract
PURPOSE Fedratinib is an oral, selective Janus kinase 2 inhibitor that is approved in the United States for the treatment of patients with intermediate-2 or high-risk myelofibrosis. Pharmacokinetics and tolerability of fedratinib in subjects with renal impairment (RI) and hepatic impairment (HI) were evaluated in two separate studies. METHODS In the renal study, male and female subjects with stable, chronic mild, moderate, and severe RI, as well as those with end-stage renal disease, were included. The hepatic study included subjects with stable, chronic mild HI. Both were phase 1, multicenter, open-label, single-dose studies, and included matched healthy subjects. Subjects received a single oral dose of fedratinib 300 mg on day 1, were discharged on day 4, returned for clinical visits on days 5-12, and had their end-of-study visit between days 14 and 16. RESULTS Thirty-six and 17 subjects were included in the renal and hepatic studies, respectively. In the renal study, fedratinib area under the plasma concentration-time curve from time 0 to infinity (AUCinf) was 1.9- and 1.5-fold higher in subjects with severe and moderate RI, respectively, than in matched healthy subjects. In the hepatic study, fedratinib AUCinf did not appreciably differ between subjects with mild HI and matched healthy subjects. Overall, most treatment-emergent adverse events were gastrointestinal and mild. CONCLUSION Mild RI and HI do not necessitate fedratinib dosage adjustments. Subjects with moderate RI should be monitored (with dosage adjustments made as necessary), whereas those with severe RI should receive a daily dose of 200 mg, reduced from the indicated dose of 400 mg.
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Affiliation(s)
- Ken Ogasawara
- Bristol Myers Squibb, 556 Morris Ave, Summit, NJ, 07901, USA
| | - William B Smith
- Alliance for Multispecialty Research, University of Tennessee, Knoxville, TN, USA
| | | | | | - Maria Palmisano
- Bristol Myers Squibb, 556 Morris Ave, Summit, NJ, 07901, USA
| | - Gopal Krishna
- Bristol Myers Squibb, 556 Morris Ave, Summit, NJ, 07901, USA.
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Kim KA, Park IB, Park JY. Effects of CYP2D6 and CYP3A5 genetic polymorphisms on steady-state pharmacokinetics and hemodynamic effects of tamsulosin in humans. Eur J Clin Pharmacol 2018; 74:1281-1289. [PMID: 29947950 DOI: 10.1007/s00228-018-2501-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 05/31/2018] [Indexed: 12/17/2022]
Abstract
PURPOSE Tamsulosin is one of the most potent drugs currently available to treat benign prostatic hyperplasia. Cytochrome P450 (CYP) 2D6 and CYP3A are the two major enzymes responsible for tamsulosin metabolism. The purpose of this study was to evaluate the effects of CYP2D6 and CYP3A5 genetic polymorphisms on the pharmacokinetics and hemodynamic effects of tamsulosin in humans. METHODS Twenty-nine male subjects were enrolled and their CYP2D6 (*2,*4,*5,*10,*14,*21,*41, and *xN) and CYP3A5 (*5) genotypes were screened. Tamsulosin was administered daily for 6 days to assess its steady-state pharmacokinetics and hemodynamic effects according to CYP2D6 and CYP3A5 genotypes. RESULTS CYP2D6 group 3 (with genotype *10/*10 or *5/*10) exhibited higher plasma levels than CYP2D6 group 1 (with genotype *1/*1,*1/*2,*1/*2xN, or *2/*10xN) or CYP2D6 group 2 (with genotype *1/*10,*1/*41, or *2/*5) (trough concentrations for groups 1, 2, and 3: 1.3, 1.8, and 3.8 ng/mL, respectively [P < 0.001]; peak concentrations for groups 1, 2, 3: 8.3, 10.0, and 13.8 ng/mL, respectively [P < 0.005]). Similarly, CYP2D6 genotypes influenced the hemodynamic effects of tamsulosin based on systolic and diastolic blood pressures. However, the CYP3A5*3 polymorphism did not affect tamsulosin plasma levels and its hemodynamic effects. CONCLUSION The CYP2D6 but not the CYP3A5 genetic polymorphisms affected the pharmacokinetics and the hemodynamic effects of tamsulosin.
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Affiliation(s)
- Kyoung-Ah Kim
- Department of Clinical Pharmacology & Toxicology, Anam Hospital, Korea University College of Medicine, 126-1, 5-Ga, Anam-dong, Seongbuk-Gu, Seoul, 136-705, South Korea
| | - In-Bae Park
- Department of Clinical Pharmacology & Toxicology, Anam Hospital, Korea University College of Medicine, 126-1, 5-Ga, Anam-dong, Seongbuk-Gu, Seoul, 136-705, South Korea
| | - Ji-Young Park
- Department of Clinical Pharmacology & Toxicology, Anam Hospital, Korea University College of Medicine, 126-1, 5-Ga, Anam-dong, Seongbuk-Gu, Seoul, 136-705, South Korea.
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Ebihara T, Shimizu H, Yamamoto M, Higuchi T, Jinno F, Tagawa Y. The effect of elevated α 1-acid glycoprotein on the pharmacokinetics of TAK-272 (SCO-272), an orally active renin inhibitor, in rats. Xenobiotica 2018; 49:584-590. [PMID: 29790816 DOI: 10.1080/00498254.2018.1480817] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
The pharmacokinetics of TAK-272 (SCO-272), an orally active renin inhibitor, was investigated in rats with subcutaneously injected turpentine oil, which was an inflammation animal model. Following intravenous administration of TAK-272 to the turpentine-treated rats, the systemic clearance and volume of distribution decreased with the elevated plasma α1-acid glycoprotein (AGP) levels. The elevated plasma AGP levels were negatively correlated with the plasma unbound fraction of TAK-272 in the rats. Although the AUCs of total TAK-272 in the turpentine-treated rats were higher than those in the control rats after intravenous and oral administration, those of unbound TAK-272, which seem to directly contribute to the pharmacological effect and safety, were nearly equal between the turpentine-treated and control rats in the respective dose routes. TAK-272 has been shown to primarily bind to AGP in the human plasma. These results strongly suggested that the pharmacokinetic of TAK-272 in humans would also be affected by the variation in the plasma AGP levels and should be discussed with not only the total concentrations but also the unbound concentrations in the clinical trial for patients with elevated plasma AGP levels.
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Affiliation(s)
- Takuya Ebihara
- a Drug Metabolism and Pharmacokinetics Research Laboratories, Pharmaceutical Research Division , Takeda Pharmaceutical Company Limited , Kanagawa , Japan
| | - Hisao Shimizu
- a Drug Metabolism and Pharmacokinetics Research Laboratories, Pharmaceutical Research Division , Takeda Pharmaceutical Company Limited , Kanagawa , Japan
| | - Masami Yamamoto
- a Drug Metabolism and Pharmacokinetics Research Laboratories, Pharmaceutical Research Division , Takeda Pharmaceutical Company Limited , Kanagawa , Japan
| | - Tomoaki Higuchi
- a Drug Metabolism and Pharmacokinetics Research Laboratories, Pharmaceutical Research Division , Takeda Pharmaceutical Company Limited , Kanagawa , Japan
| | - Fumihiro Jinno
- a Drug Metabolism and Pharmacokinetics Research Laboratories, Pharmaceutical Research Division , Takeda Pharmaceutical Company Limited , Kanagawa , Japan
| | - Yoshihiko Tagawa
- a Drug Metabolism and Pharmacokinetics Research Laboratories, Pharmaceutical Research Division , Takeda Pharmaceutical Company Limited , Kanagawa , Japan
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Shimamura M, Miyakawa J, Doi M, Okada K, Kurumatani H, Mori Y, Oshida K, Nakajo I, Oikawa K, Ushigome F, Miyashita A, Isono M, Miyamoto Y. The Pharmacokinetics of Beraprost Sodium Following Single Oral Administration to Subjects With Impaired Kidney Function. J Clin Pharmacol 2016; 57:524-535. [PMID: 27681484 DOI: 10.1002/jcph.835] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Accepted: 09/24/2016] [Indexed: 11/10/2022]
Abstract
The purpose of the present study was to evaluate the pharmacokinetics of beraprost sodium (BPS) and its active enantiomer, BPS-314d, in Japanese subjects with impaired kidney function. The plasma and urine concentrations of BPS and BPS-314d were measured following the single oral administration of 120 μg of BPS as the sustained-release tablet, TRK-100STP, under fasting conditions to 18 subjects with impaired kidney function (stage 2, 3, and 4 chronic kidney disease [CKD] as categorized by the estimated glomerular filtration rate) and to 6 age-, body weight-, and gender-matched subjects with normal kidney function (stage 1 CKD). The Cmax values (mean ± SD) of BPS in stage 1, 2, 3, and 4 CKD, respectively, were 84.9 ± 22.9, 119.8 ± 36.4, 190.6 ± 137.3, and 240.2 ± 110.5 pg/mL; its AUC0-48h were 978 ± 226, 1252 ± 427, 1862 ± 964, and 1766 ± 806 pg·h/mL, respectively, and its cumulative urinary excretion rates were 0.704 ± 0.351%, 0.638 ± 0.292%, 0.485 ± 0.294%, and 0.159 ± 0.136%. The Cmax values of BPS-314d were 22.4 ± 6.4, 30.8 ± 8.5, 46.7 ± 30.6, and 54.4 ± 25.2 pg/mL, its AUC0-48h were 155 ± 56, 226 ± 67, 341 ± 176, and 329 ± 143 pg·h/mL, and its cumulative urinary excretion rates were 0.428 ± 0.242%, 0.349 ± 0.179%, 0.356 ± 0.270%, and 0.096 ± 0.099%, respectively. Adverse events were reported in 2 subjects with stage 2 CKD and 1 subject with stage 4 CKD. The Cmax and AUC0-48h of BPS and BPS-314d were higher based on the severity of impaired kidney function. No relationship was observed between the incidence of adverse events and the severity, and tolerability was confirmed. We consider that dose adjustment is not necessary, but BPS is more carefully treated in patients with impaired kidney function.
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Affiliation(s)
- Masahiro Shimamura
- Pharmaceutical Clinical Research Department, Toray Industries, Inc, Tokyo, Japan
| | - Jun Miyakawa
- Pharmaceutical Clinical Research Department, Toray Industries, Inc, Tokyo, Japan
| | - Masaaki Doi
- Clinical Data Science & Quality Management Department, Toray Industries, Inc, Tokyo, Japan
| | - Kiyonobu Okada
- Clinical Data Science & Quality Management Department, Toray Industries, Inc, Tokyo, Japan
| | - Hajimu Kurumatani
- Pharmaceutical Clinical Research Department, Toray Industries, Inc, Tokyo, Japan
| | - Yoshitaka Mori
- Pharmaceutical Clinical Research Department, Toray Industries, Inc, Tokyo, Japan
| | - Keiyu Oshida
- Pharmaceutical Research Laboratories, Toray Industries, Inc, Kanagawa, Japan
| | - Ikumi Nakajo
- Clinical Pharmacology Global Development, Astellas Pharma Inc, Tokyo, Japan
| | - Keishi Oikawa
- Clinical Pharmacology Global Development, Astellas Pharma Inc, Tokyo, Japan
| | - Fumihiko Ushigome
- Analysis & Pharmacokinetics Research Laboratories, Drug Discovery Research, Astellas Pharma Inc, Ibaraki, Japan
| | - Aiji Miyashita
- Analysis & Pharmacokinetics Research Laboratories, Drug Discovery Research, Astellas Pharma Inc, Ibaraki, Japan
| | - Masanao Isono
- Pharmaceutical Clinical Research Department, Toray Industries, Inc, Tokyo, Japan
| | - Yohei Miyamoto
- Pharmaceutical Clinical Research Department, Toray Industries, Inc, Tokyo, Japan
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Mahmood I, Boxenbaum H. Vertical allometry: Fact or fiction? Regul Toxicol Pharmacol 2014; 68:468-74. [DOI: 10.1016/j.yrtph.2014.02.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 02/03/2014] [Accepted: 02/07/2014] [Indexed: 01/04/2023]
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Yamada M, Ohno Y, Hisaka A, Yamaguchi R, Suzuki H. Systematic Analysis of Changes in Drug Exposure in Patients with Renal Dysfunction and Their Relationships with Renal Excretion Ratio of the Drug. ACTA ACUST UNITED AC 2013. [DOI: 10.5649/jjphcs.39.660] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Up-Regulation of α
1a
and α
1d
-Adrenoceptors in the Prostate by Administration of Subtype Selective α
1
-Adrenoceptor Antagonist Tamsulosin in Patients With Benign Prostatic Hyperplasia. J Urol 2011; 186:1530-6. [DOI: 10.1016/j.juro.2011.05.048] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Indexed: 11/19/2022]
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Tsuda Y, Tatami S, Yamamura N, Tadayasu Y, Sarashina A, Liesenfeld KH, Staab A, Schäfer HG, Ieiri I, Higuchi S. Population pharmacokinetics of tamsulosin hydrochloride in paediatric patients with neuropathic and non-neuropathic bladder. Br J Clin Pharmacol 2011; 70:88-101. [PMID: 20642551 DOI: 10.1111/j.1365-2125.2010.03662.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT Tamsulosin is available on prescription as a modified release capsule in the US (Flomax), and in most European countries for the treatment of the signs and symptoms of benign prostatic hyperplasia (BPH). The pharmacokinetics of tamsulosin hydrochloride (HCl) have been extensively studied in adults, but no pharmacokinetic data for paediatrics have been published to date. WHAT THIS STUDY ADDS A population pharmacokinetic model of tamsulosin HCl was developed in paediatric patients. Covariate analysis revealed that body weight and alpha(1)-acid glycoprotein influenced both the apparent clearance and the apparent volume of distribution. This study confirms that there is no major difference in the pharmacokinetics of tamsulosin HCl between paediatrics (age range 2-16 years) and adults when the effect of body weight is taken into consideration. AIMS The main objective of this study was to characterize the population pharmacokinetics of tamsulosin hydrochloride (HCl) in paediatric patients with neuropathic and non-neuropathic bladder. A secondary objective was to compare the pharmacokinetics in paediatric patients and adults. METHODS Tamsulosin HCl plasma concentrations in 1082 plasma samples from 189 paediatric patients (age range 2-16 years) were analyzed with NONMEM, applying a one compartment model with first-order absorption. Based on the principles of allometry, body weight was incorporated in the base model, along with fixed allometric exponents. Covariate analysis was performed by means of a stepwise forward inclusion and backward elimination procedure. Simulations based on the final model were used to compare the pharmacokinetics with those in adults. RESULTS Beside the priori-implemented body weight, only alpha(1)-acid glycoprotein had an effect on both apparent clearance and apparent volume of distribution. No other investigated covariates, including gender, age, race, patient population and concomitant therapy with anti-cholinergics, significantly affected the pharmacokinetics of tamsulosin HCl (P < 0.001). The results of simulations indicated that the exposure in 12.5 kg paediatric patients was 3.5-4.3 fold higher than that in 70.0 kg adults. After a weight-based dose administration, the exposure in paediatric patients was comparable with that in healthy adults. CONCLUSIONS A population pharmacokinetic model of tamsulosin HCl in paediatric patients was established and it described the data well. There was no major difference in the pharmacokinetics of tamsulosin HCl between paediatric patients (age range 2-16 years) and adults when the effect of body weight was taken into consideration.
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Affiliation(s)
- Yasuhiro Tsuda
- Pharmacokinetics and Non-Clinical Safety Department, Nippon Boehringer Ingelheim Co., Ltd, Hyogo, Japan
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Djavan B, Handl MJ, Dianat S. Combined medical treatment using dutasteride and tamsulosin for lower urinary tract symptoms suggestive of benign prostatic hyperplasia. Expert Opin Pharmacother 2010; 11:2535-47. [DOI: 10.1517/14656566.2010.516901] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Franco-Salinas G, de la Rosette JJ, Michel MC. Pharmacokinetics and Pharmacodynamics of Tamsulosin in its Modified-Release and Oral Controlled Absorption System Formulations. Clin Pharmacokinet 2010; 49:177-88. [DOI: 10.2165/11317580-000000000-00000] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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Yamada S, Kato Y, Okura T, Kagawa Y, Kawabe K. Prediction of alpha1-adrenoceptor occupancy in the human prostate from plasma concentrations of silodosin, tamsulosin and terazosin to treat urinary obstruction in benign prostatic hyperplasia. Biol Pharm Bull 2007; 30:1237-41. [PMID: 17603160 DOI: 10.1248/bpb.30.1237] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Alpha1-adrenoceptor antagonists are clinically useful for the improvement of urinary obstruction due to benign prostatic hyperplasia (BPH), and their therapeutic effects are mediated through the blockade of prostatic alpha(1)-adrenoceptors. The present study was undertaken to predict the magnitude and duration of alpha(1)-adrenoceptor occupancy in the human prostate after oral alpha(1)-adrenoceptor antagonists. Prostatic alpha(1)-adrenoceptor-binding parameters of silodosin were estimated by measuring specific [(3)H]prazosin binding in rat prostate after oral administration of this drug. The plasma concentration of silodosin after oral administration in rats and healthy volunteers was measured using a high-performance liquid chromatographic method. The alpha(1)-adrenoceptor-binding affinities (K(i)) of silodosin, tamsulosin, and terazosin in the human prostate and plasma concentrations of tamsulosin and terazosin were obtained from the literature. Using the alpha(1)-adrenoceptor binding parameters of silodosin in rat prostate, alpha(1)-adrenoceptor occupancy in the human prostate was estimated to be around 60-70% at 1-6 h after oral administration of silodosin at doses of 3.0, 8.1, and 16.1 micromol. Thereafter, the receptor occupancy was periodically decreased, to 24% (8.1 micromol) and 54% (16.1 micromol) 24 h later. A similar magnitude and time course of alpha(1)-adrenoceptor occupancy by silodosin in the human prostate were estimated using alpha(1)-adrenoceptor-binding affinities (K(i)) in the human prostate. Despite about two orders of differences in the plasma unbound concentrations after clinically effective oral dosages of silodosin, tamsulosin, and terazosin, there was a comparable magnitude of prostatic alpha(1)-adrenoceptor occupancy by these drugs. In conclusion, the prediction of alpha(1)-adrenoceptor occupancy in the human prostate by alpha(1)-adrenoceptor antagonists may provide the rationale for the optimum dosage regimen of these drugs in the therapy of BPH.
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Affiliation(s)
- Shizuo Yamada
- Department of Pharmacokinetics and Pharmacodynamics and Center of Excellence Program in the 21st Century, University of Shizuoka School of Pharmaceutical Sciences, Sizuoka, Japan.
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Ito K, Ohtani H, Sawada Y. Assessment of alpha1-adrenoceptor antagonists in benign prostatic hyperplasia based on the receptor occupancy theory. Br J Clin Pharmacol 2006; 63:394-403. [PMID: 17052252 PMCID: PMC2203254 DOI: 10.1111/j.1365-2125.2006.02783.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
AIMS To assess the mechanistic relationship between doxazosin (alpha(1)-receptor antagonist) and receptor occupancy and a measure of pharmacological effect (Q(max), the maximum urinary flow rate) and to compare the mean receptor occupancy ratio at clinical doses of doxazosin, tamsulosin, terazosin and prazosin in benign prostatic hyperplasia (BPH). METHODS A ternary complex model, which described the mechanism of alpha(1)-receptor antagonists, was fitted to the pharmacological effects and receptor occupancy ratio data for doxazosin (standard tablet). In addition, mean receptor occupancy was calculated for other alpha(1)-receptor antagonists and the optimal receptor occupancy was evaluated. The clinical pharmacological effects of the controlled release formulation of doxazosin (doxazosin GITS) were estimated based on the receptor occupancy. RESULTS The mechanistic based model was able to describe the pharmacological effects of doxazosin. Regardless of the plasma concentrations or clinical dose of each drug, the results suggest that receptor occupancy is useful to assess quantitatively and compare the pharmacological effects of drugs with similar mechanisms of action. The clinical dosage for doxazosin GITS was estimated to be at least 8 mg and the stable pharmacological effect is expected based on the estimated receptor occupancy. CONCLUSIONS A model for Q(max) improvement in BPH based on the receptor occupancy theory was able to describe the clinical effects of the alpha(1)-receptor antagonists. Receptor occupancy is a useful index for predicting the clinical effects of alpha(1)-receptor antagonists.
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Affiliation(s)
- Kaori Ito
- Medico-Pharmaceutical Sciences, Graduate School of Pharmaceutical Sciences, Kyusyu University, Fukuoka, Japan.
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Kuribayashi T, Shimizu M, Shimada T, Honjyo T, Yamamoto Y, Kuba K, Yamamoto S. Alpha 1-acid glycoprotein (AAG) levels in healthy and pregnant beagle dogs. Exp Anim 2004; 52:377-81. [PMID: 14625401 DOI: 10.1538/expanim.52.377] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Serum alpha 1-acid glycoprotein (AAG) levels were measured in healthy beagles of various ages (66 male and 74 female) by turbidimetric immunoassay (TIA), and then separately--in pregnant beagles--by single radial immunodiffusion (SRID). The first experiment revealed that serum AAG levels ranged from 40 to 960 microg/ml (mean of 322 +/- 202 microg/ml) in male dogs, and from 47 to 833 microg/ml--in female dogs (mean of 316 +/- 199 microg/ml), without any significant sex- or age-related variation. The second experiment, however, revealed that serum AAG levels increased in all pregnant beagles and peaked in the middle of gestation at 250-1,000 microg/ml (mean of 634 +/- 246 microg/ml). In 7 of 8 dogs the AAG levels peaked about 45 days after ovulation. Despite a high value of 1,210-1,360 microg/ml being observed for serum AAG levels in 3 pregnant beagles inoculated with Staphylococcus aureus, its levels in umbilical cord blood were below the detection limit of SRID (40 microg/ml).
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Affiliation(s)
- Takashi Kuribayashi
- Laboratory of Immunology, College of Environmental and Health Sciences, Azabu University, Sagamihara, Kanagawa, Japan
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Pharmacokinetics and safety of tamsulosin in subjects with normal and impaired renal or hepatic function. Curr Ther Res Clin Exp 2001. [DOI: 10.1016/s0011-393x(01)80067-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Matsushima H, Watanabe T, Higuchi S. Effect of alpha(1)-acid glycoprotein on the pharmacokinetics of tamsulosin in rats treated with turpentine oil. J Pharm Sci 2000; 89:490-8. [PMID: 10737910 DOI: 10.1002/(sici)1520-6017(200004)89:4<490::aid-jps6>3.0.co;2-o] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The pharmacokinetics of tamsulosin (TAM) was investigated using male Sprague-Dawley rats in which plasma alpha(1)-acid glycoprotein (alpha(1)-AGP) levels were elevated by the subcutaneous injection of 0.2 mL/kg of turpentine oil. alpha(1)-AGP levels increased about eight times after turpentine oil treatment, causing a threefold decrease in plasma unbound fraction (f(u)) of TAM. When 0.3 mg/kg of TAM was dosed intravenously, total and nonrenal clearances (CL(tot) and CL(nr)) in turpentine-treated rats were 47% and 44% lower than those in nontreated controls, respectively. The area under the concentration-time curve of plasma unbound TAM (AUC(inf,u)) was lower than that in the control. When 1 mg/kg of TAM was dosed orally, oral clearance (CL(oral)) in alpha1-AGP-induced rats was 65% lower than in the control. The AUC(inf,u) and unbound oral clearance (CL(oral,u)) were nearly equal in both groups. Moreover, a positive correlation was observed between fu and CL(oral) of TAM (r(2) = 0.603, P < 0.01), whereas no correlation was observed between f(u) and CL(oral,u). The absolute bioavailability (BA) increased from 19.2% to 46.9% by induction of alpha(1)-AGP. These results suggest that decreased f(u) caused by the elevation of plasma alpha(1)-AGP level affects the pharmacokinetics of TAM, but does not affect the CL(oral,u,) which represents the hepatic metabolism of TAM.
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Affiliation(s)
- H Matsushima
- Drug Metabolism Laboratories, Yamanouchi Pharmaceutical Co., Ltd., 17-1, Hasune 3-Chome, Itabashi-ku, Tokyo 174-8612, Japan.
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