[Enoxacin concentration in seminal fluid, in prostate secretions and in prostatic adenoma tissue following oral administration or intravenous infusion]

A new method to estimate quantitatively seminal vesicle and prostate gland contributions to ejaculate

AIMS

We sought to optimize a quantitative noninvasive method to determine the concentration in their glands of origin of biochemical markers of compartments of the male genital tract as the first step towards validation of a novel method for estimation of drug concentrations in these male genital tract compartments.

METHODS

Sixty-eight men participated. We compared four collection devices to split ejaculate into fractions. Fractions were assayed for fructose and prostate specific antigen (PSA) as unique markers of the seminal vesicle and prostate, respectively. Seminal vesicle fructose and prostatic PSA were estimated using a linear regression method, based on fructose-PSA axis intercepts, and compared with an older method which solves a simultaneous series of equations.

RESULTS

A five-compartment collection device performed best with mean (95% confidence interval) PSA vs. fructose r(2) of 0.84 (0.71, 0.98, P < 0.001). Using resampling simulations, glandular PSA and fructose estimates were highly variable and often implausible when using only two fractions. Using our method, the prostate contributed 37-44% to the whole ejaculate and the seminal vesicle contributed 55-61%. The novel regression method was highly correlated (r(2) > or = 0.98) with older methods.

CONCLUSIONS

We developed a noninvasive quantitative method of male genital tract biochemical marker estimation using a five-compartment tray to collect three to five ejaculate fractions. Our novel regression method is quantitative and more fully developed than older methods. This noninvasive method for determining glandular marker concentrations should be useful to provide quantitative estimates of drug concentrations in these glands.

The role of antibiotics in chronic bacterial prostatitis

The role of antibiotic treatment in prostatitis is described. The selection of an appropriate antimicrobial agent with optimal pharmacokinetics for prostatic secretion and tissue is important, particularly in chronic bacterial prostatitis (CBP). The theoretical background of drug penetration into the prostate is outlined, emphasising the phenomenon of ion trapping and the role of non-ionic diffusion of weak acids, bases and amphoteric drugs across biological membranes with a pH gradient. Determination of drug concentrations in human prostatic secretion is problematic because of possible urinary contamination. Studies have been carried out mainly in healthy volunteers. The results must be interpreted with caution if no care was taken to rule out or at least to identify urinary contamination. Analysing the concentrations of various fluoroquinolones in prostatic and seminal fluid as well as in prostatic tissue, it becomes obvious that the fluoroquinolones differ not only in plasma concentrations but also in their penetration to these sites. In spite of intensive investigations, our knowledge is still limited regarding the mechanisms that govern the transport of antibiotics into and their activity in the various prostatic compartments and how these findings can be applied clinically. Nevertheless, the concentrations at the site of infection of most of the fluoroquinolones should be sufficient for the treatment of CBP and vesiculitis caused by susceptible pathogens.

Enoxacin: a reappraisal of its clinical efficacy in the treatment of genitourinary tract infections

Enoxacin is a 6-fluoronaphthyridinone antibacterial agent with good in vitro activity against Neisseria gonorrhoeae and most Gram-negative urinary tract pathogens. It is less active in vitro against Acinetobacter spp., Pseudomonas aeruginosa, and most Gram-positive bacteria, than against Gram-negative organisms. Enoxacin is rapidly absorbed, with a high oral bioavailability (87 to 91%). Of the absorbed dose, 44 to 56% is excreted unchanged in the urine, with peak urinary concentrations (>500 mg/L within 4 hours) remaining high (>100 mg/L) for up to 24 hours, sufficient to inhibit most urinary tract pathogens. Single (400 mg) and multiple oral dose regimens (100 to 600 mg twice or 3 times daily for 5 to 14 days) of enoxacin are as effective for the treatment of patients with complicated or uncomplicated urinary tract infections as other antibacterial agents such as amoxicillin, cefuroxime axetil, cotrimoxazole (trimethoprim-sulfamethoxazole) or trimethoprim. Noncomparative data suggest that enoxacin is also an effective agent for the treatment of prostatitis. Single 400 mgoral doses of enoxacin produce >/- 95% bacteriological cure rates in gonococcal infections, comparable to those produced by single intramuscular doses of ceftriaxone 250 mg. Perioperative doses of oral enoxacin 200 mg provide effective prophylaxis against postoperative bacteriuria after transurethral resection of the prostate. Concomitant administration of enoxacin with a number of commonly used therapeutic agents (e.g. antacids, methylxanthines, warfarin) affects the pharmacokinetic properties of either enoxacin or the coadministered agents. Enoxacin is reasonably well tolerated, with the incidence of adverse experiences ranging from 0 to 24%. Adverse events are mainly gastrointestinal, neurological or dermatological and resolve with minimal intervention. Overall, although enoxacin exhibits a number of clinical characteristics that are similar to those of other agents for the treatment of genitourinary tract infections, the advantages offered by this agent generally do not outweigh those of alternative fluoroquinolone agents. Thus, it is likely to prove to be yet another addition to the list of agents available for the management of these infections.

Drugs in semen

Over the past 50 years, a decline in the quality of semen has been observed, possibly resulting in a reduction in male fertility. Among the factors affecting semen quality, exposure to drugs is of particular importance. It is known that drugs can be transported to the seminal plasma, which is made up of secretions from the various accessory genital glands. There is evidence that many drugs enter the male genitourinary tract by an ion-trapping process. Lipid solubility and the degree of ionisation of the drug, which depend on the pH of plasma and seminal fluid, are important factors in this process. To date, few studies have been conducted on this topic. Pharmacokinetic evaluation of the fluids of the male accessory gland have been performed in the case of chloroquine and caffeine only, while the effects of mesalazine (5-aminosalicylic acid), sulfasalazine, salicylate, propranolol, diltiazem, flunarizine, verapamil, caffeine and nicotine on sperm physiology and morphology have been examined. Although data from the literature are scarce and incomplete, it is evident that many drugs can be excreted into semen. These drugs may interfere with the most common semen characteristics, potentially resulting in a male-mediated teratogenic effect, or local and systemic responses in female recipients. Therefore, it may be advisable to include, in the processes of drug development, pharmacokinetic evaluation of a drug in the semen and analysis of standard microscopic parameters of the semen. This is particularly important for drugs known to concentrate in the semen.

The role of quinolones in the treatment of chronic bacterial prostatitis

Chronic bacterial prostatitis is a rare infection but difficult to treat. Usually co-trimoxazole has been used, yet with poor results. Because of their favorable pharmacokinetics and their broad antibacterial spectrum, the newer quinolones may be a good alternative. In contrast to beta-lactam antibiotics their concentrations in prostatic fluid, in prostatic tissue and in seminal fluid are relatively high in comparison to the corresponding plasma concentrations. For prostatic fluid measurements, however, possible urinary contamination has to be considered and identified otherwise falsely high levels are measured. A total of 23 studies with the newer quinolones (norfloxacin, ciprofloxacin, ofloxacin, pefloxacin, enoxacin, temafloxacin and rufloxacin) in the treatment of chronic bacterial prostatitis are available. However, the results of these studies are difficult to compare because not all investigators used the same diagnostic criteria and there was a considerable range of duration of treatment and of follow-up. Since the issue involved in the treatment of prostatitis is that of relapse, patients cannot be considered cured if they have been followed for one week or one month only. There were four studies among the 23 publications, i.e. one with norfloxacin and three with ciprofloxacin, which fulfilled the criteria of standardized prostatic localization and of long-term follow-up of at least six months. The results are promising, but further investigations, especially controlled studies, are needed in order to determine the role of the newer quinolones in the treatment of chronic bacterial prostatitis.