Prevention of urinary tract infection and bacteremia following transurethral surgery: oral lomefloxacin compared to parenteral cefotaxime

Chemical synthesis and biological activities of 16α-derivatives of 5α-androstane-3α,17β-diol as antiandrogens

In our efforts to develop compounds with therapeutic potential as antiandrogens, we synthesized a series of 5alpha-androstane-3alpha,17beta-diol derivatives with a fixed side-chain length of 3-methylenes at C-16alpha, but bearing a diversity of functional groups at the end. Among these, the chloride induced the best antiproliferative activity on androgen-sensitive Shionogi cells. Substituting the OH at C-3 by a methoxy group showed the importance of the OH. Moreover, its transformation into a ketone increased the androgen receptor (AR) binding but decreased the antiproliferative activity and induced a proliferative effect on Shionogi cells. These results confirm the importance of keeping a 5alpha-androstane-3alpha,17beta-diol nucleus instead of a dihydrotestosterone nucleus. Variable side-chain lengths of 2-, 3-, 4-, and 6-methylenes at C-16alpha were investigated and the optimal length was found to be 3-methylenes. Although exhibiting a weak AR binding affinity, 16alpha-(3'-chloropropyl)-5alpha-androstane-3alpha,17beta-diol (15) provided an antiproliferative activity on Shionogi cells similar to that of pure non-steroidal antiandrogen hydroxy-flutamide (77% and 67%, respectively, at 0.1 microM). The new steroidal compound, 15, thus constitutes a good starting point for development of future antiandrogens with a therapeutic potential against prostate cancer.

Novel C-17-heteroaryl steroidal CYP17 inhibitors/antiandrogens: synthesis, in vitro biological activity, pharmacokinetics, and antitumor activity in the LAPC4 human prostate cancer xenograft model

New chemical entities, steroidal C-17 benzoazoles (5, 6, 9 and 10) and pyrazines (14 and 15) were rationally designed and synthesized. The key reaction for synthesis of the benzoazoles involved the nucleophilic vinylic "addition-elimination" substitution reaction of 3beta-acetoxy-17-chloro-16-formylandrosta-5,16-diene (2) and benzoazole nucleophiles, while that for synthesis of pyrazines involved palladium-catalyzed cross-coupling reaction of 17-iodoandrosta-5,16-dien-3beta-ol (13) with tributylstannyl diazines. Some of the compounds were shown to be potent inhibitors of human CYP17 enzyme as well as potent antagonist of both wild type and mutant androgen receptors (AR). The most potent CYP17 inhibitors were 3beta-hydroxy-17-(1H-benzimidazole-1-yl)androsta-5,16-diene (5, code named VN/124-1), 3beta-hydroxy-17-(5(1)-pyrimidyl)androsta-5,16-diene (15) and 17-(1H-benzimidazole-1-yl)androsta-4,16-dien-3-one (6), with IC(50) values of 300, 500 and 915 nM, respectively. Compounds 5, 6, 14 and 15 were effective at preventing binding of (3)H-R1881 (methyltrienolone, a stable synthetic androgen) to both the mutant LNCaP AR and the wild-type AR, but with a 2.2- to 5-fold higher binding efficiency to the latter. Compounds 5 and 6 were also shown to be potent pure AR antagonists. The cell growth studies showed that 5 and 6 inhibit the growth of DHT-stimulated LNCaP and LAPC4 prostate cancer cells with IC(50) values in the low micromolar range (i.e., <10 microM). Their inhibitory potencies were comparable to that of casodex but remarkably superior to that of flutamide. The pharmacokinetics of compounds 5 and 6 in mice were investigated. Following s.c. administration of 50 mg/kg of 5 and 6, peak plasma levels of 16.82 and 5.15 ng/mL, respectively, occurred after 30 to 60 min, both compounds were cleared rapidly from plasma (terminal half-lives of 44.17 and 39.93 min, respectively), and neither was detectable at 8 h. Remarkably, compound 5 was rapidly converted into a metabolite tentatively identified as 17-(1H-benzimidazol-1-yl)androsta-3-one. When tested in vivo, 5 proved to be very effective at inhibiting the growth of androgen-dependent LAPC4 human prostate tumor xenograft, while 6 was ineffective. Compound 5 (50 mg/kg/twice daily) resulted in a 93.8% reduction (P = 0.00065) in the mean final tumor volume compared with controls, and it was also significantly more effective than castration. To our knowledge, this is the first example of an antihormonal agent (an inhibitor of androgen synthesis (CYP17 inhibitor)/antiandrogen) that is significantly more effective than castration in suppression of androgen-dependent prostate tumor growth. In view of these impressive anticancer properties, compound 5 is a strong candidate for development for the treatment of human prostate cancer.

Do antimicrobials have a role in preventing septicaemia following instrumentation of the urinary tract?

Urinary tract instrumentation is a significant cause of septicaemia. Review of the literature suggests that selective use of antimicrobials would reduce the risk of septicaemia as this varies between patients and with procedures. Antimicrobial prophylaxis is indicated for patients at high risk of endocarditis, or who are neutropenic. For patients without these risk factors, it is indicated for open, transurethral, or certain forms of laser prostatectomy or trans-rectal prostate biopsy. For cystoscopy, antimicrobials are indicated for patients with preoperative bacteriuria or a preoperative indwelling catheter. Single dose aminoglycosides or oral fluoroquinolones are the agents of choice with the exception of the prevention of endocarditis, where combinations active against streptococci are recommended. For other instrumentations, the risk of antimicrobial toxicity probably outweighs the benefits and a risk-reduction strategy is recommended. Further studies are required to provide definitive answers in many of these areas.

Effects of new 17alpha-hydroxylase/C(17,20)-lyase inhibitors on LNCaP prostate cancer cell growth in vitro and in vivo

Our laboratory has been developing new inhibitors of a key regulatory enzyme of testicular and adrenal androgen synthesis 17alpha-hydroxylase/C(17,20)-lyase (P450c17), with the aim of improving prostate cancer treatment. We designed and evaluated two groups of azolyl steroids: delta5-non-competitive inhibitors (delta5NCIs), VN/63-1, VN/85-1, VN/87-1 and their corresponding delta4 derivatives (delta4NCIs), VN/107-1, VN/108-1 and VN/109-1. The human P450c17 gene was transfected into LNCaP human prostate cancer cells, and the resultant LNCaP-CYP17 cells were utilized to evaluate the inhibitory potency of the new azolyl steroids. VN/85-1 and VN/108-1 had the lowest IC50 values of 1.25 +/- 0.44 nM and 2.96 +/- 0.78 nM respectively, which are much lower than that of the known P450 inhibitor ketoconazole (80.7 +/- 1.8 nM). To determine whether the compounds had direct actions on proliferation of wild-type LNCaP cells, cell growth studies were performed. All of the delta5NCIs and VN/108-1 blocked the growth-stimulating effects of androgens. In steroid-free media, the delta5NCIs decreased the proliferation of LNCaP cells by 35-40%, while all of the delta4NCIs stimulated LNCaP cells growth 1.5- to 2-fold. In androgen receptor (AR) binding studies, carried out to determine the mechanism of this effect, all of the delta4NCIs (5 microM) displaced 77-82% of synthetic androgen R1881 (5 nM) from the LNCaP AR. The anti-androgen flutamide and the delta5NCIs displaced 53% and 32-51% of R1881 bound to AR respectively. These results suggested that the delta5NCIs may also be acting as anti-androgens. We further evaluated our inhibitors in male severe combined immunodeficient mice bearing LNCaP tumour xenografts. In this model VN/85-1 was as effective as finasteride at inhibiting tumor growth (26% and 28% inhibition, respectively) and the inhibitory effect of VN/87-1 was similar to that of castration (33% and 36% inhibition respectively). These results suggest that VN/85-1 and VN/87-1 may be potential candidates for treatment of prostate cancer.

An economic analysis of antimicrobial prophylaxis against urinary tract infection in patients undergoing transurethral resection of the prostate

Despite the high level of safety and low incidence of mortality associated with transurethral resection of the prostate (TURP), urinary tract infections (UTIs)-the most common complication associated with this procedure-continue to be an important source of postoperative morbidity and costs. However, there is controversy about whether antimicrobial agents should be used as UTI prophylaxis in patients undergoing TURP and, if so, which agents should be used and for what duration. This retrospective study used multivariate regression analysis to evaluate the different types and durations of antibiotic prophylaxis in 222 patients who underwent TURP at a Veterans Affairs hospital between January 1, 1995, and March 30, 1998. The primary outcome measures were total medical costs (ie, medication use, clinic office visits, and hospital care in the 4 weeks after the procedure), length of hospital stay (total days in hospital due to the procedure), and probability of UTI (incidence of infection in the 4 weeks after the procedure). Results showed that there was no difference in the length of hospital stay regardless of the regimen or duration of pre-TURP antibiotic therapy. Patients who received pre-TURP ampicillin plus ceftizoxime incurred moderately higher total medical costs than did patients who received the least costly drug, cefazolin (P = 0.10). Similarly, patients who received post-TURP quinolones incurred a significantly higher total medical cost than did patients who received co-trimoxazole (P = 0.06). We found no evidence of a relationship between use of specific parenteral or oral antibiotic prophylaxis for UTI in patients undergoing TURP and the rate of UTI in such patients. Thus there is no justification for the use of more expensive antibiotic regimens. At our institution, the preferred pre-TURP prophylactic regimen would be cefazolin, whereas co-trimoxazole would be the most cost-effective post-TURP prophylactic regimen. Because duration of post-TURP prophylaxis does not appear to influence the rate of UTI, 24 hours would seem adequate.

Cytochrome P450c17-expressing Escherichia coli as a first-step screening system for 17alpha-hydroxylase-C17,20-lyase inhibitors

We have designed and synthesized a number of cytochrome P450 17alpha-hydroxylase-C17,20-lyase (P450c17) inhibitors with the aim of inhibiting androgen synthesis. To select the most potent inhibitors, we initially used human testicular microsomes, which have a high level of expression of this enzyme. However, due to lack of availability of human tissue and variability among the samples, we utilized recombinant human enzyme expressed in Escherichia coli. We designed a simple and economical protocol based on the report that recombinant bovine P450c17 can be functionally active in live bacteria. In the assay we report here, we substituted high-performance liquid chromatography product isolation with a rapid biochemical acetic acid releasing assay and utilized intact P450c17-expressing E. coli for the source of the enzyme. Enzymatic parameters of the bacterial system (Km = 5.1 x 10(-7) M, Vmax = 15.0 pmol/min/mg) were similar to those of human testicular microsomes (Km = 4.8 x 10(-7) M, Vmax = 40.0 pmol/min/mg), and our compounds displayed a similar pattern of inhibition in both systems. This new system is a fast, reliable, and reproducible method for screening P450c17 inhibitors. Furthermore, it eliminates our dependence on human tissue and potential data fluctuations caused by variations in enzymatic activity between donors.

Single-dose antibiotic prophylaxis in transurethral resection of the prostate: a prospective randomized trial

OBJECTIVE

To evaluate the efficacy of single-dose antibiotic prophylaxis in transurethral resection of the prostate (TURP).

PATIENTS AND METHODS

A total of 139 patients were entered into a prospective randomized trial comparing single-dose antibiotic prophylaxis with no antibiotic before surgery. Twelve patients were excluded because they had significant bacteriuria before surgery (defined as > or = 10(5) bacteria/mL). Of the remaining 127 patients, 62 were allocated to the single-dose group (A) and 65 to the no-antibiotic group (B). All 62 patients in group A received 1 g of ceftriaxone intravenously 1-2 h before surgery with the anaesthetic premedication, the 65 in group B receiving none. Urine cultures were collected post-operatively as the catheter was removed and again 4 weeks after hospitalization.

RESULTS

The incidence of post-operative bacteriuria was statistically significantly different, occurring in five patients (9%) in group A and 16 patients (26%) in group B (Fisher's exact test, one-tail P = 0.009). There was no significant difference between the groups 4 weeks after hospitalization. The overall incidence of bacteriuria post-operatively and 4 weeks after hospitalization was 11 patients (18%) in group A and 22 patients (34%) in group B (P = 0.03).

CONCLUSION

Single-dose antibiotic prophylaxis with 1 g of ceftriaxone intravenously is effective in patients undergoing TURP and is recommended for such surgery.

Antibiotic prophylaxis for patients undergoing transurethral resection of the prostate

OBJECTIVES

To evaluate the prevention of urinary tract infections (UTIs) after transurethral resection of the prostate (TURP) in a prospective randomized study using a quinolone antibiotic (fleroxacin) to compare the efficacy of: (1) a single oral dose, (2) a single intravenous (IV) dose, and (3) an extended regimen consisting of an initial IV dose followed by oral therapy until removal of the urinary catheter, but for less than 6 days.

METHODS

We excluded from study patients who received antimicrobial agents within 48 hours of surgery. Single-dose prophylaxis consisted of 400 mg of fleroxacin given either orally or intravenously. The extended regimen consisted of an initial 400 mg IV dose followed by 400 mg oral each day (patients older than 75 years, or with a creatinine clearance less than 40 mL/min, received 200 mg/day). UTI was defined as clinical evidence of infection plus the presence of more than 10 white blood cells (WBC)/mm3 in any urine specimen plus the presence of more than 10(4) cfu/mL in midstream urine specimens or more than 10(2) cfu/mL in catheter specimens.

RESULTS

Prior to TURP, 30% (25/84) of the patients had a urethral catheter in situ and 12% (3/25) of these patients had bacteriuria. Only 1 patient developed a UTI and that was 22 days after a TURP (intergroup comparisons, Fisher's exact test greater than 0.05). There were no instances of urosepsis.

CONCLUSIONS

A single oral dose of a fluoroquinolone agent provided optimum prophylaxis for patients undergoing TURP.

[Antibiotic prophylaxis in urology. Surgical and endoscopic surgery. Lithotripsy. Transplantation]

The opening of the urinary tract switches surgical and endoscopic urology to the clean contaminated category and therefore for each of them antibiotic prophylaxis has to be considered. Prophylactic antibiotics are only recommended before surgery in patients with sterile urine. Those with infected urine should have curative antibiotics. Prophylactic antibiotics are commonly recommended for transurethral resection of the prostate, transrectal biopsy of the prostate, renal transplant and radical cystectomy with ileal or colonic pouch for urinary diversion. It is worthless in diagnostic cystoscopy. ESWL and scrotal surgery. For other procedures more data are required to conclude.