Alpha blocker prazosin for the treatment of benign prostatic hypertrophy (BPH).SV Punekar, AR Kelkar, PM Gavande, NR Rao, JA Date, AR Prem
Department of Urology, KEM and Seth GS Medical College Hospital, Parel, Mumbai.
In this study medical treatment with alpha blocker-prazosin is compared with transurethral resection of prostate (TURP) in 62 patients suffering from benign enlargement of prostate with a gland size of less than 20 gms. After thorough interrogation patients were offered either TURP or prazosin therapy. Symptom scoring, residual volume of urine and urinary flow rates were estimated in both the groups before and 3 months after the therapy. 23.5% patients in prazosin group while 90% of patients in TURP group had significant improvement. This distinctly brings out the superiority of TURP for benign enlargement of prostate.
Keywords: Adrenergic alpha-Antagonists, therapeutic use,Comparative Study, Human, Male, Prazosin, therapeutic use,Prostatic Hyperplasia, drug therapy,surgery,Transurethral Resection of Prostate, Treatment Outcome, Urination, physiology,
Prostatectomy has gained widespread acceptance for the treatment of BPH. However, in the last two years there has been an inclination towards non surgical treatment modalities. The use of a blockers is one of them. The distribution of alpha receptors in pro-static stroma and the smooth muscle of pre-pro-static sphincter zone is well established.
The characterisation of these receptors is done in human as well as canine prostates. Relaxation of this smooth muscle by alpha blockade results in relief of symptoms due to benign pro-static hypertrophy (BPH). Various studies have proved the therapeutic efficacy of blockers, selective and non-selective, in -9 the treatment of BPH,,,,,,,,.
Though there have been double blind control studies of various agents against placebo, there has not been a substantial evidence to replace the transurethral resection - TURR by medical therapy,. In this study results of Prazosin, (alpha blockers) administered for pro-static obstruction are compared with those of TURP The aim was to select a patient population in whom medical treatment could replace and avoid invasive surgical approach.
A total of 62 patients were enrolled for this study. All these patients had estimated gland size of less than 209m on clinical examination and cystos-copy. None had any episode of retention of urine or significant residue. After thorough interrogation 42 patients opted for Prazosin therapy and 20 patients chose to undergo TURR
These patients were evaluated with pre-treatment symptom scoring based on the symptom score chart designed by Boyarsky. Madsen and Lepor, as shown in [Table - 1]. The maximum score as per this table could be 12 and criteria for inclusion was a minimum score of 6. Measurement of residual volume of urine and uroflowmetry was carried out in all of them.
Those patients who opted for Prazosin were given the drug in a dose of 1 mg BD increasing to a total maximum dose of 6 mg/day depending on the response. Any adverse side effects like postural hypotension and giddiness were noted.
All these patients were followed up at 6 weeks. 3, 6 and 12 months with post - treatment symptom scoring urinary flow rates and residual amount of urine estimation.
The patients who did not show improvement with Prazosin at 6 months were subjected to TURP. All the parameters were estimated again to judge the treatment response to TURP.
Twenty patients selected TURP as a therapeutic option. In these patients all the parameters were assessed before and after operative procedure. Statistical tests were applied to compare the results of treatment in both the groups.
Of 42 patients given Prazosin therapy, only 10 patients (23.8%) showed significant improvement in symptom scoring and urinary flow rates. Remaining patients though partially relieved of their symptoms, did not have statistically significant improvement [Table - 2]. Two patients who did not show any improvement were subjected to TURR
The results of TURP are shown in [Table - 3]. Of 20 patients subjected primarily for TURP, 18 patients (90%) showed remarkable improvement in symptom scoring and urinary flow. Two patients who did not improve were found to have hypo-tonic detrusor on subsequent investigations.
[Table - 4] shows the results in thirteen patients who tailed to respond to Prazosin but had dramatic increase in urinary flow and reduction of symptoms following TURP.
The beneficial effects of Prazosin have been studied in BPH. Various studies have found approximately 75% - 100% improvement in symptom scoring and urinary flow rates following alpha blockers [Table - 5].
With TURP they had dramatic reduction of symptoms and significant increase in the flow rates. Thus TURP is beneficial as the reliable single procedure which eliminates problems of compliance for prolonged medical therapy and the danger of retention during the medical therapy.
The effect of these alpha blockers is by inhibiting the dynamic component of BPH. This component is actually the smooth muscle distributed in bladder neck, pro-static stroma and pro-static capsule. Relaxation of this smooth muscle releives the functional obstruction. Initially phenoxy-benzamine was advocated for treatment of the pro-static obstruction. But this has side effects of both alpha1 and alpha2 blocking action. Since it is undesirable, selective alpha, blockers became popular. Prazosin has gained popularity in this group, being less expensive, easily available and with minimum side effects.
TURP works by resecting the obstructive adenoma, thus removing both the organic and the dynamic component of BPH and is found to be useful in 75% to 90% of patients,. Then if Prazosin and TURP have similar results, why not resort to only the medical line of therapy and avoid surgery?
However, in our present study we found significant improvement in only 23.8% of patients with Prazosin. Other patients though symptomatically better (score wise) cannot be taken as indicators of successful therapy. Side effects were minimum but long-term therapy is required. On the other hand TURP wag an excellent mode with more than 200% improvement in 90% of patients as one time therapy.
The non-responders to Prazosin who subsequently underwent TURP form an important group highlighting the difference between two treatment modalities.
Thus according to the present study TURP appears to be the Gold standard of therapy in the patients with BPH. We feel that Prazosin should be reserved only for those:
1. Who do not wish to undergo surgery.
2. Unfit for surgery.
3. Require symptomatic relief temporarily.
[Table - 1], [Table - 2], [Table - 3], [Table - 4], [Table - 5]