The Pharmacokinetic Profile of Tamsulosin Oral Controlled Absorption System (OCAS®)

Development of Sustained Release System Based on High Water-Absorbable Gel Formation Using Croscarmellose Sodium, Alkaline Excipients and HPMC (ACSH SR System); Novel Application of Croscarmellose Sodium as a Gel Former

PURPOSE

Croscarmellose sodium, generally used as a superdisintegrant in pharmaceutical formulations, is hydrolyzed to form the gel structure under basic pH conditions. Utilizing this property of croscarmellose sodium, we developed a novel sustained release (SR) system.

METHODS

Immediate release (IR) and SR tablets containing croscarmellose sodium, alkaline excipients and/or hydroxypropyl methylcellulose (HPMC) were prepared and examined for wet strength and in vitro drug release behavior. In vivo oral drug absorption was evaluated for IR tablets, HPMC tablets and our novel SR tablets in fasted Beagle dogs.

RESULTS

To form the gel structure even under the physiological condition, alkaline excipients were added into the formulation containing croscarmellose sodium. Furthermore, HPMC was used to make the gel structure strong enough against mechanical destructive forces. The novel alkalized croscarmellose sodium-HPMC (ACSH) SR tablet, consisting of croscarmellose sodium, alkaline excipients, and HPMC, successfully sustained the release of acetaminophen, ibuprofen, or nicardipine hydrochloride, compared with the IR tablets. The ACSH SR system provided a better release of acetaminophen than the HPMC tablet without croscarmellose sodium in the release study using a small volume of liquid, suggesting that substantial release and subsequent absorption would be expected in the distal intestinal segments after oral dosing. The in vivo oral absorption study revealed that the ACSH SR system successfully suppressed and prolonged the plasma concentrations of acetaminophen.

CONCLUSION

This novel ACSH SR system prepared with croscarmellose sodium, alkaline excipients, and HPMC, would be a promising SR formulation for enabling substantial drug absorption in the distal intestinal segments.

Oral Drug Delivery Systems Applied to Launched Products: Value for the Patients and Industrial Considerations

Drug delivery systems (DDS) control the amount, rate, and site of administration of drug substances in the body as well as their release and ADME (absorption, distribution, metabolism, excretion). Among the various types of DDS, amount-controlled DDS for solubilization and absorption increase the bioavailability. Time- and amount-controlled DDS are controlled release formulations classified as (1) membrane-type, (2) matrix-type, (3) osmotic-type, and (4) ion-exchange type. Timed-release formulations also control the time and amount of release and the absorption of drugs. Site- and amount-controlled DDS are characterized by colonic delivery and intestinal lymph-targeting to improve release and ADME of drug substances. Finally, site-, time-, and amount-controlled DDS are gastroretentive formulations and local delivery in the oral cavity to improve site retention, release, and ADME of drugs. DDS can enhance efficacy, reduce adverse effects, and optimize the dosing frequency of various drug products to increase patient value. This review focuses on patient value and industrial considerations of launched oral DDS. We provide a technological overview of candidate and marketed DDS, as well as the pros/cons of the technologies for industrialization with consideration to excipients, manufacturing, and storage stability. Moreover, to demonstrate the usefulness of the technology and support the selection and development of the best technologies for patients, we also describe patient value from clinical studies and analyses, particularly with regard to increased new medical options, higher efficacy, reduced adverse effects, reduced number of doses and clinic visits, easier administration, higher quality of life, greater adherence, and satisfaction.

Drug-Drug Interactions between Tamsulosin and Mirabegron in Healthy Individuals Do Not Affect Pharmacokinetics and Hemodynamic Parameters Significantly

Overactive bladder (OAB) is characterized by urinary urgency and increased urinary frequency, substantially affecting quality of life. Tamsulosin and mirabegron combination therapy has been studied as a safe and effective treatment option for patients with OAB. This study evaluated the effects of combining these two drugs on their pharmacokinetics and safety profiles in healthy Korean males. In this open-label, fixed-sequence, three-period, drug-drug interaction phase 1 study, a total of 36 male participants were administered multiple doses of tamsulosin alone (0.2 mg once daily), mirabegron alone (50 mg once daily), or a combination of both drugs. The results showed that the combination of tamsulosin and mirabegron increased tamsulosin exposure in the plasma by approximately 40%. In contrast, the maximum plasma concentration of mirabegron was reduced by approximately 17% when administered with tamsulosin. No clinically significant changes in the safety profiles, vital signs, or clinical laboratory test results were observed in this study. In conclusion, there were no clinically relevant drug-drug interactions between tamsulosin and mirabegron in terms of pharmacokinetics, safety, and tolerability, suggesting that their combination could be a promising treatment option for patients with OAB.

Characterization of Channeling Effects Applied to Extended-Release Matrix Tablets Containing Pirfenidone

Pirfenidone (PRF) is an anti-fibrotic agent that has been approved by the Food and Drug Administration (FDA) for the treatment of mild to moderate idiopathic pulmonary fibrosis. However, the current oral administration dosing regimen of PRF is complex and requires high doses. Patients are instructed to take PRF three times daily, with each dose consisting of up to three capsules or tablets (600 mg/d or 1.8 g/d of PRF) taken with food. To improve the dosing regimen, efforts are being made to develop an extended-release tablet with a zero-order release pattern. In this study, two types of extended-release matrix tablets were compared: non-channeled extended-release matrix tablets (NChMT) and channeled extended-release matrix tablets (ChMT). In vitro release tests, swelling and erosion index, rheology studies, and X-ray microcomputed tomography (XRCT), were conducted. The results indicated that ChMT maintained a zero-order release pattern with a constant release rate, while NChMT exhibited a decreased release rate in the latter half of the dissolution. ChMT exhibited accelerated swelling and erosion compared to other formulations, and this was made possible by the presence of channels within the tablet. These channels allowed for thorough wetting and swelling throughout the entire depth of the tablet. The formation of channels was confirmed through XRCT images. In conclusion, the presence of channels in ChMT tablets increased the rate of swelling and erosion, resulting in a zero-order release pattern. This development offers the potential to improve the dosage of PRF and reduce its associated side effects.

Factors Associated With Nocturia-Related Quality of Life in Men With Lower Urinary Tract Symptoms and Treated With Tamsulosin Oral Controlled Absorption System in a Non-Interventional Study

Nocturia impairs quality of life (QoL). We have performed a non-interventional study in which men with lower urinary tract symptoms (LUTS) were treated for at least 3 months with tamsulosin oral controlled absorption system (0.4 mg q.d.). Other than observing efficacy and tolerability of this drug formulation, the study was designed to explore the relative roles of number of nocturia episodes and of non-urological causes of nocturia on nocturia-related QoL at baseline and treatment-associated changes thereof. The study enrolled 5775 men seeking treatment of their LUTS. Tamsulosin improved LUTS, e.g. International Prostate Symptom Score from 19.5 ± 5.9 to 10.1 ± 4.9 (means ± SD). This was associated by clinically meaningful improvements in the Nocturia QoL score (from 45 ± 19 to 73 ± 17 points) and other QoL scores. Number of nocturnal voids was the key driver of all QoL scores at baseline; change of number of nocturia episodes that of improvement of all QoL scores upon treatment. In contrast, non-urological causes of nocturia such as heart failure, diabetes, sleep apnea, fluid or alcohol intake or use of diuretics or hypnotics had only small if any effects on baseline QoL or treatment-associated improvements thereof. The observed effects of non-urological causes on QoL apparently were largely driven by their effect on number of nocturnal voids. These data further support the idea that improvement of nocturia may be an important treatment goal in male LUTS.

Interactions between medications employed in treating benign prostatic hyperplasia and food - A short review

Benign prostatic hyperplasia (BPH) is the most common disease in elderly men. BPH symptoms include frequent urination, urgent tenesmus and urination at night, a weak and interrupted urine flow and a sense of incomplete emptying of the bladder. Alpha- 1 adrenergic receptor antagonists and 5 α-reductase inhibitors form the most important groups of medications employed in BPH. Appropriately managed BPH patients shall be subject to counselling on interactions between agents belonging to these groups, and on particular components of the food they have. The present review has been aimed at assessing potential effects of consumed food, alcohol and fruit juices on the pharmacokinetics and pharmacodynamics of medications for benign prostatic hyperplasia. The authors reviewed the English PubMed database covering the years 1991-2015. Additionally, a digital version of Stockley Drugs Interaction and other electronic databases such as drugs.com and Medscape were also researched; characterisation charts for particular medical products were also analyzed. Pharmacokinetics of extended-release forms of alfuzosin, doxazosin, tamsulosin and silodosin is well known to be food-sensitive. Alfuzosin, tamsulosin and silodosin due to their likely interaction with grapefruit juice and citrus fruits, may intensify adverse effects of the drugs. Alpha-1 adrenergic receptor antagonists are known to interact with alcohol, leading to orthostatic hypotension. For 5 alpha-reductase inhibitors, such as finasteride, or dutasteride, the pharmacokinetic effect due to consumed food is of no clinical importance and thus they may be taken regardless of meals. As in general grapefruit juice and alcohol tend to significantly affect the efficacy and safety of the applied drug therapy, it is highly advisable to be knowledgeable on the subject in order to educate patients.

[Trade-offs in oral drug product development]

Drug products are developed to meet multiple targets, thereby increasing their value. Pharmaceutical scientists encounter several trade-offs during the development of novel oral formulations. These trade-offs are generated by their desire to supply the highest possible quality products under the prevailing conditions of limited time and cost, and feasible options. When there are two incompatible factors, it is sometimes difficult to dismiss one element. This is because a quality target product profile (QTPP) is critical for each product being developed, and all elements should basically be satisfied with the criteria. Therefore, technological innovation becomes important to overcome the trade-offs. This article introduces examples of such innovations which have been successful in doing this, as well as some encountered in the oral formulation development and in the selection of proper dosage forms. Based on these examples, points to be considered in order to produce the drug product are thoroughly discussed.

Effects of food intake on the pharmacokinetic properties of mirabegron oral controlled-absorption system: a single-dose, randomized, crossover study in healthy adults

BACKGROUND

Mirabegron is a β3-adrenoceptor agonist used for the treatment of overactive bladder. Mirabegron is formulated as an extended-release tablet using oral controlled-absorption system (OCAS) technology.

OBJECTIVE

This study was designed to assess the effects of food on the pharmacokinetic properties of mirabegron OCAS in accordance with regulatory requirements to support dosing recommendations.

METHODS

In this single-dose, randomized, open-label, 3-period, parallel-dose-group, crossover study, mirabegron OCAS 50 or 100 mg was administered orally to healthy adult subjects in the fasted state or after a high- or low-fat breakfast. Dose administrations were separated by a washout period of at least 10 days. Blood samples were drawn up to 96 hours after dosing, and plasma concentrations of mirabegron were analyzed by LC/MS-MS. PK properties were determined using noncompartmental methods. Primary end points for the assessment of food effects were Cmax and AUC0-∞. For tolerability assessment, adverse events (AEs) were monitored using investigators' questionnaires and subjects' spontaneous reports, vital sign measurements, hematology, clinical chemistry, and ECG.

RESULTS

Thirty-eight subjects (male, 50%; mean age, 32.1 years; mean weight, 77.3 kg; race, 76.3% white) were enrolled in the 50-mg dose group and 38 subjects (male, 52.6%; mean age, 30.9 years; mean weight, 74.5 kg; race, 63.2% white) in the 100-mg dose group. With either fed condition or dose, the 90% CIs for the fed/fasted ratios of both Cmax and AUC0-∞ of mirabegron fell below the predetermined range for bioequivalence (80.0%-125.0%), suggesting that food had no effect on exposure to mirabegron OCAS. With the 50-mg dose, mirabegron Cmax was reduced by 45% with a high-fat breakfast compared with fasted conditions (geometric mean ratio [GMR], 54.8% [90% CI, 43.7%-68.6%]) and AUC0-∞, by 17% (GMR, 83.2% [90% CI, 74.2%-93.4%]). With the 100-mg dose, mirabegron Cmax and AUC0-∞ were reduced by 39% (GMR, 61.3% [90% CI, 47.8%-78.7%]) and 18% (82.4% [72.6%-93.5%]), respectively, after a high-fat breakfast. With the 50-mg dose, mirabegron Cmax was decreased by 75% (GMR, 25.0% [90% CI, 19.9%-31.3%]) and AUC0-∞ by 51% (48.7% [43.3%-54.7%]) after a low-fat breakfast. Corresponding reductions with the 100-mg dose were 64% (GMR, 36.3% [90% CI, 28.2%-46.8%]) for Cmax and 47% (GMR, 53.2% [90% CI, 46.8%-60.5%]) for AUC0-∞. The fed/fasted ratios for mirabegron Cmax and AUC0-∞ were in general independent of dose or sex. Food delayed Tmax compared with the fasted state, with similar increases with the high- and low-fat meals (0.9 hours with 50 mg and 1.5-2.0 hours with 100 mg). Mirabegron was generally well tolerated, with no apparent difference in AE frequency between the fasted and fed states.

CONCLUSIONS

Mirabegron OCAS tablets exhibited a decrease in mirabegron plasma exposure with food that was independent of dose (50 or 100 mg) or gender but dependent on meal composition. A greater reduction in mirabegron exposure was observed after a low-fat breakfast compared with after a high-fat breakfast. Based on findings from previous studies, the effects of food observed in this study do not warrant dose adjustment in clinical practice. ClinicalTrials.gov identifier: NCT00939757.

Intestinal absorption mechanism of mirabegron, a potent and selective β₃-adrenoceptor agonist: involvement of human efflux and/or influx transport systems

Mirabegron, a weak-basic compound, is a potent and selective β3-adrenoceptor agonist for the treatment of overactive bladder. Mirabegron extended release formulation shows dose-dependent oral bioavailability in humans, which is likely attributable to saturation of intestinal efflux abilities leading to higher absorption with higher doses. This study evaluated the membrane permeability of mirabegron and investigated the involvement of human intestinal transport proteins in the membrane permeation of mirabegron. Transcellular transport and cellular/vesicular uptake assays were performed using Caco-2 cells and/or human intestinal efflux (P-glycoprotein [P-gp], breast cancer resistance protein [BCRP], and multidrug resistance associated protein 2 [MRP2]) and influx (peptide transporter 1 [PEPT1], OATP1A2, and OATP2B1) transporter-expressing cells, vesicles, or Xenopus laevis oocytes. The absorptive permeability coefficients of mirabegron in Caco-2 cells (1.68-1.83 × 10(-6) cm/s) at the apical and basal pH of 6.5 and 7.4, respectively, were slightly higher than those of nadolol (0.97-1.41 × 10(-6) cm/s), a low permeability reference standard, but lower than those of metoprolol and propranolol (both ranged from 8.49 to 11.6 × 10(-6) cm/s), low/high permeability boundary reference standards. Increasing buffer pH at the apical side from 5.5 to 8.0 gradually increased the absorptive permeation of mirabegron from 0.226 to 1.66 × 10(-6) cm/s, but was still less than the value in the opposite direction (11.0-14.2 × 10(-6) cm/s). The time- and concentration-dependent transport of mirabegron was observed in P-gp-expressing cells and OATP1A2-expressing oocytes with apparent Km values of 294 and 8.59 μM, respectively. In contrast, no clear BCRP-, MRP2-, PEPT1-, or OATP2B1-mediated uptake of mirabegron was observed in their expressing vesicles or cells. These findings suggest that mirabegron has low-to-moderate membrane permeability and P-gp is likely to be involved in its efflux into the lumen in the intestinal absorption process. The results also suggest that mirabegron could possibly be transported by intestinal influx transporters as well as simple diffusion.

Determination of tamsulosin in human plasma by liquid chromatography/tandem mass spectrometry and its application to a pharmacokinetic study

Tamsulosin, a selective α₁-adrenoceptor antagonist, is used for the treatment of benign prostatic hyperplasia (BPH). We developed and validated a rapid, sensitive, and simplified liquid chromatography analytical method utilizing tandem mass spectrometry (LC-MS/MS) for the determination of tamsulosin in human plasma. After liquid-liquid extraction with methyl t-butyl ether, chromatographic separation of tamsulosin was achieved using a reversed-phase Luna C₁₈ column (2.0 mm × 50 mm, 5 μm particles) with a mobile phase of 10 mM ammonium formate buffer (pH 3.5)-methanol (25:75, v/v) and quantified by MS/MS detection in ESI positive ion mode. The flow rate of the mobile phase was 200 μL/min and the retention times of tamsulosin and the internal standard (IS, diphenhydramine) were 0.8 and 0.9 min, respectively. The calibration curves were linear over a range of 0.01-20 ng/mL (r>0.999). The lower limit of quantification using 500 μL of human plasma was 0.01 ng/mL. The mean accuracy and precision for intra- and inter-day validation of tamsulosin were both within acceptable limits. The present LC-MS/MS method showed improved sensitivity for quantification of tamsulosin in human plasma compared with previously described analytical methods. The validated method was successfully applied to a pharmacokinetic study in humans.

The effect of food on the oral bioavailability of drugs: a review of current developments and pharmaceutical technologies for pharmacokinetic control

Here we review the mediation of the food effects on drugs by pharmaceutical technologies. The pharmacokinetics of drugs are affected by the interaction of drugs with food, which changes drug physicochemical and physiological properties (food effects). Several pharmaceutical technologies may be used to control food effects. Drugs exhibit different patterns of solubilization depending on release formulations. Formulations such as nanoparticle, solid dispersion and cyclodextrin systems, may control the solubility and release of insoluble drugs. Other controlled-release technologies, such as osmotic-controlled release or colon-specific delivery systems may also control food effects. As the structure of drug candidates becomes more complex, different methods of investigation, such as in vitro and in vivo correlation and in silico simulation will be required to predict drug characteristics and food effects.

Effects of strong CYP2D6 and 3A4 inhibitors, paroxetine and ketoconazole, on the pharmacokinetics and cardiovascular safety of tamsulosin

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

Tamsulosin metabolism involves both CYP2D6 and 3A4. However, data on potential drug-drug interactions between tamsulosin and inhibitors of CYP2D6 and 3A4 are limited and information on potential pharmacodynamic consequences of such pharmacokinetic interactions is missing.

WHAT THIS STUDY ADDS

This study provides information on the drug-drug interactions of tamsulosin with strong CYP2D6 and strong CYP3A4 inhibitors after single dose administration in healthy subjects.

AIM

To determine the effect of the strong CYP2D6 inhibitor paroxetine and strong CYP3A4 inhibitor ketoconazole on the pharmacokinetics and safety (orthostatic challenge) of tamsulosin.

METHODS

Two open-label, randomized, two-way crossover studies were conducted in healthy male volunteers (extensive CYP2D6 metabolizers).

RESULTS

Co-administration of multiple oral doses of 20 mg paroxetine once daily with a single oral dose of the 0.4 mg tamsulosin HCl capsule increased the adjusted geometric mean (gMean) values of C(max) and AUC(0,∞) of tamsulosin by factors of 1.34 (90% CI 1.21, 1.49) and 1.64 (90% CI 1.44, 1.85), respectively, and increased the terminal half-life (t(1/2) ) of tamsulosin HCl from 11.4 h to 15.3 h. Co-administration of multiple oral doses of 400 mg ketoconazole once daily with a single oral dose of the 0.4 mg tamsulosin increased the gMean values of C(max) and AUC(0,∞) of tamsulosin by a factor of 2.20 (90% CI 1.96, 2.45) and 2.80 (90% CI 2.56, 3.07), respectively. The terminal half-life was slightly increased from 10.5 h to 11.8 h. These pharmacokinetic changes were not accompanied by clinically significant alterations of haemodynamic responses during orthostatic stress testing.

CONCLUSION

The exposure to tamsulosin is increased upon co-administration of strong CYP2D6 inhibitors and even more so of strong 3A4 inhibitors, but neither PK alteration was accompanied by clinically significant haemodynamic changes during orthostatic stress testing.

Specific pharmacokinetic aspects of the urinary tract

This chapter reviews the evidence for "specific" pharmacokinetics playing a role in currently marketed drugs intended to treat lower urinary tract (LUT) symptoms. Principles of drug targeting include intrinsic properties of drugs or organs as well as drug formulations to modify drug release or to create confinement of drug presence. Prodrugs and specific formulations to deliver high drug concentrations at the site(s) of action as well as other ways to manipulate drug distribution to achieve enrichment in target tissues are considered. In overactive bladder (OAB), specific formulations for oxybutynin have been introduced to reduce the level of side effects of the active drug. Extended release tablet formulations and a topical gel formulation have been introduced, with efficacy similar to immediate release (IR) tablets, but with a reduction in anticholinergic adverse effects. However, these modifications have not led to outstanding performance parameters compared to other anticholinergic drugs marketed as IR formulations. Urinary excretion is discussed as potential mechanism for targeting LUT symptoms, but no strong indications appear to exist that this mechanism would contribute for currently available drugs. Intravesical administration of drugs is not a preferred option and only considered for drugs like botulinum toxin, where the inconvenient application compensates for a reasonable degree of long-term efficacy in severe refractory OAB. Alpha acid glycoprotein binding is discussed as a potential factor to influence drug tissue distribution, and it is concluded that there is reasonable evidence that for tamsulosin this mechanism is responsible for the difference in free fraction of the drug observed in plasma and prostate, which could contribute to its relative absence of blood pressure effects in patients with LUT symptoms related to benign prostate hyperplasia (LUTS-BPH). The principle of irreversible inhibition of type II 5α-reductase as a tool to develop drugs to reduce prostatic levels of dihydrotestosterone is employed by both dutasteride and finasteride for treatment of LUTS-BPH. Of the mechanisms discussed, the principles employed for the 5α-reductase blockers and tamsulosin in this respect can be considered relatively specific for its urological indication.

Tamsulosin modified release and oral controlled absorption system in the management of lower urinary tract symptoms suggestive of benign prostatic hyperplasia

BACKGROUND

Tamsulosin MR has been on the market for the treatment of lower urinary tract symptoms suggestive of benign prostatic hyperplasia (LUTS/BPH) for many years. Recently, tamsulosin OCAS was introduced, which has improved pharmacokinetics.

OBJECTIVE

To evaluate the efficacy and safety of tamsulosin.

METHODS

Literature was identified through a PubMed search using the term 'tamsulosin' and by screening reference lists of review articles.

RESULTS

Tamsulosin rapidly improves LUTS/BPH, with benefits maintained in the long-term. The overall tolerability of tamsulosin MR 0.4 mg is comparable to that of placebo. While the efficacy of tamsulosin OCAS and MR is comparable, tamsulosin OCAS is slightly better tolerated.

CONCLUSION

Tamsulosin OCAS 0.4 mg has a favourable efficacy/safety profile and should be considered the treatment of choice for patients requiring optimal symptom control without increasing the risk of cardiovascular adverse events.

Behaviour and transit of tamsulosin Oral Controlled Absorption System in the gastrointestinal tract

OBJECTIVE

To assess the in vivo behaviour, gastric emptying time and gastrointestinal transit of the new tablet formulation of tamsulosin which uses the Oral Controlled Absorption System (OCAS) technology and to relate gastrointestinal transit parameters to the profile of the plasma concentration time curve.

RESEARCH DESIGN AND METHODS

After breakfast, 8 healthy male subjects received a single tamsulosin OCAS 0.4 mg tablet labelled with 4MBq technetium-99m. Scintigraphic images were taken immediately after dosing, every 15 min until 15 h post-dose and at 24 h post-dose. Blood samples for pharmacokinetic analysis were taken up to 24 h after dosing. Safety was assessed by physical examinations, vital signs, laboratory safety evaluations and adverse events monitoring.

RESULTS

A mean C(max) of 7.84 +/- 2.54 ng/mL was achieved after 5.13 +/- 1.25 h (t(max)). The mean gastric emptying time for the tablet was 4.1 +/- 2.5 h. Mean transit time through the small intestine was 3.6 +/- 2.9 h; the mean colonic arrival time 7.7 +/- 2.9 h post-dose and the mean release time (spread of the technetium-99m label from the tablet core) 12.3 +/- 1.7 h post-dose. In all cases where release of the radiolabelled tablet was observed, this occurred within the colon. Variations in gastric residence, small intestinal transit or colonic residence did not apparently influence release time or site.

CONCLUSIONS

The results suggest that tamsulosin is released from the OCAS formulation throughout the entire gastrointestinal tract, including the colon, indicating consistent and continued 24-h drug release. This correlates with a more consistent pharmacokinetic profile.

Comparison of the Cardiovascular Effects of Tamsulosin Oral Controlled Absorption System (OCAS®) and Alfuzosin Prolonged Release (XL)

OBJECTIVE

The cardiovascular (CV) effects of tamsulosin oral controlled absorption system (OCAS) 0.4 mg were compared with those of alfuzosin prolonged release (XL) 10 mg.

METHODS

Two single-dose, crossover studies were performed. In study 1, CV alpha1-adrenoceptor antagonism was assessed by measuring the inhibition of phenylephrine (PE)-induced increases in diastolic blood pressure (DBP) and total peripheral resistance (TPR) before and after dosing with placebo, tamsulosin OCAS, and alfuzosin XL in 18 young subjects. In study 2, orthostatic stress tests (OTs) were performed before and after dosing with tamsulosin OCAS and alfuzosin XL in 40 elderly subjects. Pharmacokinetics were assessed in both studies.

RESULTS

In study 1, tamsulosin OCAS induced statistically significantly less inhibition of PE-induced increases in DBP at 2 h after dosing and in TPR at 2 and 4 h after dosing than alfuzosin XL. In study 2, tamsulosin OCAS had a lower incidence of positive OTs than did alfuzosin XL, with the difference between both treatments being statistically significant at 6h after dosing and for all time points after dosing combined. This was in line with smaller changes in vital signs observed for tamsulosin OCAS. The t(max) values for both treatments were comparable.

CONCLUSIONS

Tamsulosin OCAS 0.4 mg produces smaller vascular effects than does alfuzosin XL 10 mg.

Medikamentöse BPS-Therapie

5alpha-Reductase inhibitors and alpha(1)-receptor blockers are established options for symptomatic treatment of benign prostatic hyperplasia (BPH). Achieving maximum efficacy is contingent on correct dosage and requires careful patient selection in view of the substance class employed. All applicable preparations exert only a low-grade effect on prostatic obstruction. This condition should be excluded by appropriate urological examination before treatment is initiated. If the patient's distress is minor, refraining from drug therapy can be considered. Symptomatic patients with small prostate volume are suited for monotherapy with alpha(1)-receptor blockers and symptomatic patients with large prostate volume profit from combination therapy. When 5alpha-reductase inhibitors are used, BPH patients should be made aware of the findings from the Prostate Cancer Prevention Trial.