Prazosin HCl

α₁ and α_2B-adrenoceptor antagonist. Also a potent antagonist at the melatonin MT₃ receptor (K_i = 10.2 nM). Also available as part of the α₁-Adrenoceptor and Mixed Adrenergic

The efficacy of prazosin HCl in the treatment of urinary flow obstruction due to prostatic hypertrophy.[Pubmed:1690480]

Urol Int. 1990;45 Suppl 1:4-17.

Prazosin HCl was administered to 20 patients with urinary obstructions associated with prostatic hypertrophy. Significant reductions were recorded in the nighttime and the mean 24-hour urination frequencies. Patient-assessed symptoms diminished significantly, and uroflowmetry revealed significant increases in average and maximum urine flow rates. Residual urine volume decreased, the residual urine ratio declined, and bladder compliance tended to increase. The Prazosin HCl therapy produced no significant effects on blood pressure or pulse rate, and no side effects appeared. The therapy was judged to be 'extremely beneficial' in 10%, 'beneficial' or better in 50%, and 'marginally beneficial' or better in 85% of all the patients.

Effects of an alpha 1-adrenergic blocker (prazosin HCl) on micturition disturbances associated with benign prostatic hypertrophy.[Pubmed:1690479]

Urol Int. 1990;45 Suppl 1:36-9.

The effects of Prazosin HCl treatment on several variables were determined in 16 patients suffering from micturition disturbances associated with benign prostatic hypertrophy. After administration of the drug in doses of 1-2 mg/day, subjective symptoms improved in 11 patients (68.8%). Urine retention rate, maximum urine flow rate, and average urine flow rate exhibited statistically significant improvement, but voided urine volume did not. Urethral pressures declined significantly in the bladder neck and prostatic urethra but not in the pressure at the external sphincter. The results suggest Prazosin HCl may be effective in small doses in symptomatic treatment of benign prostatic hypertrophy.

Effects of prazosin HCl on micturition disturbance associated with benign prostatic hypertrophy and bladder neck contracture.[Pubmed:1690477]

Urol Int. 1990;45 Suppl 1:26-9.

The effects of alpha 1-adrenergic blockade with Prazosin HCl were examined in 28 patients with benign prostatic hypertrophy and bladder neck contracture. The patients received 2-3 mg of Prazosin HCl daily administered orally. Improvement in subjective symptoms was observed in 75% of the patients. We evaluated clinical effects as the minimum time of micturition (calculated as the ratio of voided volume/maximum flow rate) for voided volumes less than 200 ml and the maximum flow rates and average flow rates for voided volumes over 200 ml. Evaluation of the findings on a flow rate nomogram revealed improvement in maximum flow rates and average flow rates in 41% of the patients. Side effects such as dizziness developed in only 1 patient.

Effects of prazosin HCl on the urethral pressure profile in patients with benign prostatic hyperplasia.[Pubmed:1690478]

Urol Int. 1990;45 Suppl 1:30-5.

The effects of Prazosin HCl on the urethral pressure profile (UPP) were studied in 14 patients with benign prostatic hyperplasia. Urethral pressure profilometry was performed 1 h after oral administration of 1 or 2 mg Prazosin HCl. Functional profile and continence zone lengths were significantly reduced following administration of 1 or 2 mg Prazosin HCl, as compared with the pretreatment lengths. The administration of 2 mg Prazosin HCl resulted in a significant decrease in prostatic peak pressure, whereas the maximum urethral closure pressure exhibited an insignificant decrease. The results suggest that the effects of Prazosin HCl on UPP were dose dependent within the range from 1 to 2 mg.

Characterization of 2-[125I]iodomelatonin binding sites in Syrian hamster peripheral organs.[Pubmed:10381796]

J Pharmacol Exp Ther. 1999 Jul;290(1):334-40.

The neurohormone melatonin is a key agent in synchronizing the circadian rhythms. At least three types of binding sites have been described for melatonin: the G-coupled, seven-transmembrane domain receptors mt1 and MT2 and a putative binding site called MT3. The latter has been described in hamster brain membranes, and its binding capacity is optimum at 4 degrees C. We further characterized this binding site on other peripheral hamster tissues, including intestine, liver, kidney, lung, muscle, and heart. We found a high level of binding sites (>30 fmol/mg of protein) in intestine and kidney. Furthermore, we completed the existing pharmacological profile of this site, which can now be described as 2-iodomelatonin > 6-chloromelatonin > methy-isobutyl-amiloride > acridine orange > 5-methylcarbonylamino-N-acetyltryptamine > prazosin > N-acetylserotonin > melatonin. This profile was found in all the hamster organs tested that had a large number of binding sites, namely, brain, intestine, kidney and liver. Furthermore, when comparisons were possible, the MT3 pharmacological characteristics were similar to those described in the literature for hamster brain and testis. This profile was compared to the pharmacology obtained on human cloned mt1 and MT2 receptors and proved to be completely different, as expected. We provide new evidence for an alternate melatonin binding site not only in hamster brain but also in some peripheral organs.

Prazosin inhibits MK-801-induced hyperlocomotion and dopamine release in the nucleus accumbens.[Pubmed:8864686]

Eur J Pharmacol. 1996 Aug 1;309(1):1-11.

This study examined the putative inhibitory effect of the alpha 1-adrenoceptor antagonist prazosin (1-(4-amino-6,7-dimethoxy-2-quinazolinyl)-4-(2-furanylcarbonyl)pip erazine) on changes evoked by the psychotomimetic, non-competitive NMDA receptor antagonist, MK-801((+)-5-methyl-10,11-dihydroxy-5H-dibenzo-(a,d)cyclohepten-5, 10-imine), in locomotor activity and extracellular concentrations of dopamine and its metabolites, dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), and the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) in the nucleus accumbens as assessed by microdialysis in freely moving rats. MK-801 (0.1 and 0.3 mg/kg, s.c.) induced a significant, dose-dependent increase in horizontal locomotor activity but did not affect rearing. Prazosin administration alone (1 mg/kg, s.c.) only slightly reduced horizontal activity during an initial 10 min measurement period, although it consistently reduced rearing. However, pretreatment with prazosin effectively suppressed the locomotor stimulation caused by either dose of MK-801 throughout the whole observation period, i.e. 40 min. Both doses of MK-801 significantly increased extracellular levels of dopamine in the nucleus accumbens up to approximately 90%. In addition, MK-801 dose dependently increased dopamine metabolite concentrations in the nucleus accumbens, but 5-HIAA was significantly increased only by the high dose of MK-801. When given alone, prazosin did not affect either dopamine, DOPAC, HVA or 5-HIAA levels. However, prazosin pretreatment effectively blocked MK-801-evoked increases in dialysate dopamine concentrations. Consequently, the potent and selective alpha 1-adrenoceptor antagonist prazosin was found to specifically suppress MK-801-evoked, but not basal dopamine release in the nucleus accumbens, while effectively blocking MK-801-evoked locomotor stimulation with only negligible effects on basal locomotor activity. Thus, alpha 1-adrenoceptor antagonism may act by reducing the sensitivity of the mesolimbic dopamine system to pharmacological or environmental challenge. Since most antipsychotic drugs exhibit both dopamine D2 receptor and alpha 1-adrenoceptor antagonistic properties, they may alleviate psychosis not only through blockade of postsynaptic dopamine receptors, but also presynaptically on the mesolimbic dopamine system, through their alpha 1-adrenoceptor antagonistic action. This latter action may contribute to reduce evoked dopamine hyperactivity, e.g. in response to stress.

Pharmacological characterization of melatonin binding sites in Syrian hamster hypothalamus.[Pubmed:2157597]

Eur J Pharmacol. 1990 Jan 3;175(1):71-7.

The radioligand [125I]iodomelatonin was used to study melatonin binding sites in Syrian hamster hypothalamus and hippocampus. Scatchard analysis revealed a single binding site with nanomolar affinity in hypothalamus (Kd = 1.8 +/- 0.3 nM, Bmax = 75 +/- 7 fmol/mg protein; n = 4) and hippocampus (Kd = 2.2 +/- 0.2 nM, Bmax = 49 +/- 5 fmol/mg protein; n = 4). The Kd value calculated from the association and dissociation rate constants in hypothalamus was (k-1/k1) = 2.4 nM. Regional studies revealed that the highest binding of [125I]iodomelatonin occurs in the hypothalamus. Only indoles structurally related to melatonin exhibited significant affinity at this site. Prazosin was found to be a potent inhibitor of [125I]iodomelatonin binding in all brain regions studied. The pharmacological profile of this binding site indicated it to be unique, since serotonergic, dopaminergic and adrenergic drugs (other than prazosin) did not have appreciable affinity for it. Although saturation studies revealed only one binding site, the low Hill coefficients obtained for several inhibitors suggest that [125I]iodomelatonin labels multiple sites (or affinity states) in the hypothalamus.

Prazosin hydrochloride is an alpha-adrenergic blocker and is a sympatholytic drug used to treat high blood pressure and anxiety, PTSD, and panic disorder.

Prazosin HCl,19237-84-4,Natural Products,Adrenergic Receptor, buy Prazosin HCl , Prazosin HCl supplier , purchase Prazosin HCl , Prazosin HCl cost , Prazosin HCl manufacturer , order Prazosin HCl , high purity Prazosin HCl