Secretion of metronidazole into the human semen

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.

Pharmacokinetic and pharmacodynamic studies of the effect of ketoconazole on reproductive function in male rats

A single oral dose (300 mg kg-1) of ketoconazole induced reversible immobilization of rat epididymal spermatozoa at 8-24 h after dosing. This occurred when the drug concentrations in cauda epididymal fluid and seminal plasma were at their peak (18.0 +/- 7.3 and 13.5 +/- 3.0 micrograms ml-1, respectively), and which was preceded by a peak plasma concentration (Cmax) of 64.82 +/- 2.47 micrograms ml-1 at 5.15 +/- 0.68 h (Tmax). In contrast, rete testis fluid collected from the same animals contained only minute amounts of ketoconazole (0.47 +/- 0.34 micrograms ml-1). Plasma testosterone concentration showed a sharp decline within 4 h of dosing, followed by a recovery from suppression, even after administration of a low dose (100 mg kg-1) which did not affect sperm motility. These findings suggest that ketoconazole gains access to the post-testicular sex organs and affects the mature spermatozoa therein much more readily than it affects testicular spermatogenesis. Synthesis and screening of compounds with a related molecular structure but which exhibit more pronounced spermicidal and less pronounced anti-androgenic effects are thus suggested in the hope that rapidly acting and reversible male contraceptives might be identified and developed.

The effect of ketoconazole on fertility of male rats

The effect of ketoconazole on the fertility of male rats was evaluated. Three days of oral dosing with ketoconazole at 200 mg/kg reduced fertility compared to controls. A complete loss of fertility was observed after doses of 400 mg/kg. There was no change in the testicular weight, epididymal sperm concentration or epididymal weight between the control and treatment groups. Motility was reduced in the high-dose group and forward progression was reduced in both dosing groups compared to control. These data support previous observations in the dog and primate that orally administered ketoconazole alters sperm viability. Although ketoconazole is too toxic for contraceptive application, its derivatives may be useful for this purpose.

Cyclophosphamide in the seminal fluid of treated males: transmission to females by mating and effect on pregnancy outcome

Cyclophosphamide is an anticancer and immunosuppressant drug administered to men of reproductive age. In the present study the ability of cyclophosphamide and/or its metabolites to enter secretions of the male reproductive tract, to be transmitted to the female partner upon mating, and to alter progeny outcome was assessed. [14C]Cyclophosphamide was given intravenously to adult male Sprague-Dawley rats; radiolabel (greater than 96% cyclophosphamide) was first found in seminal vesicle fluid within 10 min and equilibrated with plasma radioactivity within 30 min. Furthermore, radiolabel from cyclophosphamide given to the male was transmitted to the female upon mating up to 5 hr post-drug treatment. To study possible consequences of paternal treatment with cyclophosphamide on pregnancy outcome, male rats were administered a single dose of cyclophosphamide, 10, 30, or 100 mg/kg, or saline immediately prior to cohabitation with females in proestrus. There was no effect on the number of pregnant females per sperm-positive females but there was a significant decrease in the number of implantations per pregnant female per male and in the number of live fetuses per pregnant female per male. There was a twofold increase in preimplantation loss. There was no increase in postimplantation loss or number of abnormal fetuses. These results demonstrate that cyclophosphamide not only penetrates the male reproductive tract but that it can be transmitted to the female partner and can affect progeny outcome.

Orally administered ketoconazole rapidly appears in seminal plasma and suppresses sperm motility

Ketoconazole has been shown to exert spermatostatic effects in vitro on ejaculated dog, monkey, and human spermatozoa. Oral administration of the compound to adult male beagle dogs (50-246 mg/kg) or rhesus monkeys (85-100 mg/kg) was associated with a decline in motility of sperm in ejaculates obtained after dosing. In dogs the decline in sperm motility was correlated with the presence of ketoconazole in the seminal plasma, although the measured concentrations of ketoconazole were no more than one tenth that needed for in vitro activity. The serum levels of testosterone in the dogs receiving oral ketoconazole were profoundly suppressed but the extreme rapidity of onset of the ex vivo effect on sperm motility, which was noted within 4 hours of dosing, makes it unlikely that testosterone withdrawal plays more than a minor role in the spermatostasis. The results in animals invite further pursuit of this novel, rapid onset, reversible, single dose use of spermatostatic agents for their potential as male contraceptives.