Alfuzosin HCl

Functionally uro-selective α₁ adrenoceptor antagonist that does not discriminate between α₁ subtypes. Inhibits increases in intraurethral pressure caused by phenylephrine-induced contraction by 81% with minor cardiovascula

Spectrophotometric Determination of Alfuzosin HCl in Pharmaceutical Formulations with some Sulphonephthalein Dyes.[Pubmed:23674990]

Int J Biomed Sci. 2006 Sep;2(3):273-8.

Bromocresol purple (BCP), bromophenol blue (BPB) and bromothymol blue (BTB) were used to determine alfuzosin hydrochloride either in pure form or in pharmaceutical formulations. Alfuzosin was extracted as an ion-pair complex from sample solution containing KCl-HCl buffer pH2.2, 2.4 and 2.6 into CHCl3 and the absorbance was measured at 407, 413 and 412nm with use of the cited reagents, respectively. The analytical parameters and their effects on the reported systems are investigated. The reactions were extremely rapid at room temperature and the absorbance values remains unchanged up to 24 h. Beer's law was obeyed in the concentration ranges 1.20-38.3, 0.85-46.0 and 0.63-34.0 mug/ml and detection limits were 0.28, 0.24 and 0.18 mug/ml with BCP, BPB and BTB, respectively. Recoveries were 98.80-101.33%. Interferences of the other ingredients and excipients were not observed. The proposed method is simple, fast and sensitive, and the first reported extractive method for the determination of alfuzosin in commercial tablets.

Effects of different alpha-1 adrenoceptor blockers on proximal urethral function using in vivo isovolumetric pressure changes.[Pubmed:16428864]

J Smooth Muscle Res. 2005 Oct;41(5):247-56.

The effects of different alpha-1 adrenoceptor blockers on the urethra and the cardiovascular system were evaluated using an in vivo isovolumetric intra-urethral pressure model in New Zealand white rabbits. The urethra of anesthetized male rabbits was cannulated through the bladder and secured at the vesico-urethral junction. The distal side of urethra under the pubic bone was also closed to allow measurement of the intra-urethral pressure. Both the intra-urethral pressure and the femoral arterial pressure were monitored. The effects of five different alpha-1 adrenoceptor blockers on the increases in both the intra-urethral pressure and blood pressure induced by phenylephrine were then examined. The inhibition rate of the alpha-1 adrenoceptor blockers prazosin, bunazosin, terazosin, alfuzosin and tamsulosin on the increase in intra-urethral pressure caused as a result of contraction by phenylephrine was 87.5 +/- 4.5% (mean +/- S.E.), 88.0 +/- 7.2%, 86.2 +/- 6.2%, 81.4 +/- 4.8% and 92.5 +/- 5.0% respectively. The potency ranking of these alpha-1 adrenoceptor blockers was tamsulosin > bunazosin > prazosin > terazosin > alfuzosin. Their inhibition rate of the arterial pressure increase induced by phenylephrine was 81.9 +/- 5.0%, 86.2 +/- 5.9%, 76.0 +/- 6.0%, 63.6 +/- 5.7% and 58.0 +/- 5.2% respectively, with a potency ranking of bunazosin > prazosin > terazosin > alfuzosin > tamsulosin. We therefore conclude that the alpha-1 adrenoceptor blockers bunazosin and prazosin have a more potent action on both the urethra and the vascular system. However, tamsulosin and alfuzosin displayed a marked blockade of the increased urethral pressure induced by phenylephrine, with much less of a blockade of arterial pressure. In the present study, tamsulosin has been shown to be the most sensitive and powerful of the alpha-1 adrenoceptor blockers on urethral smooth muscle.

Alfuzosin hydrochloride for the treatment of benign prostatic hyperplasia.[Pubmed:12892027]

Am J Health Syst Pharm. 2003 Jul 15;60(14):1426-39.

The chemistry, pharmacology, pharmacokinetics, clinical efficacy, and adverse effects of alfuzosin hydrochloride in the treatment of benign prostatic hyperplasia (BPH) are discussed. Alfuzosin is a functionally uroselective alpha 1-adrenergic antagonist indicated for the management of moderate to severe BPH. It can improve urinary voiding symptoms and increase urinary flow rates while causing few cardiovascular adverse effects. When administered as an immediate-release (IR) formulation, alfuzosin must be administered twice or thrice daily. The extended-release (ER) formulations of alfuzosin for once- or twice-daily administration are associated with small variations in peak and trough serum drug levels, which may contribute to the lower frequency of cardiovascular adverse effects reported with ER versus IR alfuzosin. Alfuzosin has been shown to improve patients' perception of quality of life, allowing patients to increase their physical activities and improve their ability to handle day-to-day activities. Less significant improvements in patients' sense of well-being and improved sexual functioning have been reported. The usual dose of alfuzosin for patients with BPH is 2.5 mg twice or thrice daily of the IR formulation or 5 mg of ER alfuzosin twice daily or 10 mg of ER alfuzosin once daily. The Food and Drug Administration is currently reviewing the ER 10-mg formulation for once-daily administration. IR alfuzosin is similar to all other second-generation alpha 1-adrenergic antagonists in mechanism of action, clinical efficacy, and adverse effects. No dosage titration is needed for ER alfuzosin, and its onset of peak action is within days of the start of treatment.

Comparison of the relaxant effects of alfuzosin, phentolamine and sildenafil on rabbit isolated corpus cavernosum.[Pubmed:12780851]

BJU Int. 2003 Jun;91(9):873-7.

OBJECTIVE: To compare the direct relaxant effects of alfuzosin, phentolamine and sildenafil in rabbit isolated corpus cavernosum (CC) pre-contracted with phenylephrine or KCl. MATERIALS AND METHODS: Penile erectile tissue was obtained from male New Zealand White rabbits (22-26 weeks old). The CC was cut into longitudinal strips and mounted under 2 g resting tension in 5-mL jacketed organ baths containing a modified Krebs solution bubbled with 95% O2, 5% CO2 and maintained at 37 degrees C. Tissue strips were pre-contracted by 60 mmol/L KCl or 10 micro mol/L phenylephrine. After obtaining a stable plateau of contractions, test compounds were added to the organ bath. The relaxant potencies were expressed as the percentage of inhibition of the plateau of contraction induced by 10 micro mol/L phenylephrine. RESULTS: Alfuzosin showed a concentration-dependent relaxing effect on rabbit CC pre-contracted by 10 micro mol/L phenylephrine, with a mean (sd) pIC50 of 7.64 (0.06). The relaxant effect was unaffected by pre-incubation with 100 micro mol/L Nomega-nitro-l-arginine methyl ester (L-NAME). Phentolamine had a potency similar to alfuzosin, with a pIC50 of 7.44 (0.08). Both alfuzosin and phentolamine were completely ineffective on the plateau of contraction induced by 60 mmol/L KCl. In contrast to alfuzosin, sildenafil was equipotent in relaxing the rabbit CC against each contractile agent, with pIC50 values of 7.25 (0.09) and 7.23 (0.22) with 10 micro mol/L phenylephrine and 60 mmol/L KCl, respectively. The relaxant response to sildenafil was partly blocked by pretreatment with 100 micro mol/L L-NAME, with pIC50 values of 7.94 (0.09) and 6.63 (0.32) without and with L-NAME, respectively. Sildenafil, incubated for 45 min at 10 micro mol/L, had no relaxant effect on the resting tension of the preparation or on the concentration-response curve to phenylephrine. CONCLUSIONS: The direct relaxant effect of alfuzosin is mediated through alpha1-adrenoceptor blockade. The relaxations induced by phentolamine and alfuzosin are independent of nitric oxide, whereas those induced by sildenafil are, at least partly, sensitive to L-NAME and a selective soluble guanylate cyclase inhibitor, indicating the involvement of nitric oxide and soluble guanylate cyclase. Alfuzosin and phentolamine effectively counteract alpha1-adrenoceptor-mediated contractions of rabbit CC. If valid for human CC, such an effect may contribute to an improved erectile function in patients treated for benign prostatic hyperplasia.