Screening the in vitro sperm-immobilizing effect of some anticancer drugs

Exposure to Chemotherapy During Childhood or Adulthood and Consequences on Spermatogenesis and Male Fertility

Over the last decade, the number of cancer survivors has increased thanks to progress in diagnosis and treatment. Cancer treatments are often accompanied by adverse side effects depending on the age of the patient, the type of cancer, the treatment regimen, and the doses. The testicular tissue is very sensitive to chemotherapy and radiotherapy. This review will summarize the epidemiological and experimental data concerning the consequences of exposure to chemotherapy during the prepubertal period or adulthood on spermatogenic progression, sperm production, sperm nuclear quality, and the health of the offspring. Studies concerning the gonadotoxicity of anticancer drugs in adult survivors of childhood cancer are still limited compared with those concerning the effects of chemotherapy exposure during adulthood. In humans, it is difficult to evaluate exactly the toxicity of chemotherapeutic agents because cancer treatments often combine chemotherapy and radiotherapy. Thus, it is important to undertake experimental studies in animal models in order to define the mechanism involved in the drug gonadotoxicity and to assess the effects of their administration alone or in combination on immature and mature testis. These data will help to better inform cancer patients after recovery about the risks of chemotherapy for their future fertility and to propose fertility preservation options.

FDA-approved medications that impair human spermatogenesis

We herein provide an overview of the single-ingredient U.S. Food and Drug Administration (FDA)-approved drugs that affect human spermatogenesis, potentially resulting in a negative impact on male fertility. To provide this information, we performed an in-depth search of DailyMed, the official website for FDA-approved drug labels. Not surprisingly, hormone-based agents were found to be the drugs most likely to affect human spermatogenesis. The next category of drugs most likely to have effects on spermatogenesis was the antineoplastic agents. Interestingly, the DailyMed labels indicated that several anti-inflammatory drugs affect spermatogenesis, which is not supported by the peer-reviewed literature. Overall, there were a total of 65 labels for drugs of various classes that showed that they have the potential to affect human sperm production and maturation. We identified several drugs indicated to be spermatotoxic in the drug labels that were not reported in the peer-reviewed literature. However, the details about the effects of these drugs on human spermatogenesis are largely lacking, the mechanisms are often unknown, and the clinical impact of many of the findings is currently unclear. Therefore, additional work is needed at both the basic research level and during clinical trials and post-marketing surveillance to fill the gaps in the current knowledge. The present findings will be of interest to physicians and pharmacists, researchers, and those involved in drug development and health care policy.

FDA-approved drugs that are spermatotoxic in animals and the utility of animal testing for human risk prediction

PURPOSE

This study reviews FDA-approved drugs that negatively impact spermatozoa in animals, as well as how these findings reflect on observations in human male gametes.

METHODS

The FDA drug warning labels included in the DailyMed database and the peer-reviewed literature in the PubMed database were searched for information to identify single-ingredient, FDA-approved prescription drugs with spermatotoxic effects.

RESULTS

A total of 235 unique, single-ingredient, FDA-approved drugs reported to be spermatotoxic in animals were identified in the drug labels. Forty-nine of these had documented negative effects on humans in either the drug label or literature, while 31 had no effect or a positive impact on human sperm. For the other 155 drugs that were spermatotoxic in animals, no human data was available.

CONCLUSION

The current animal models are not very effective for predicting human spermatotoxicity, and there is limited information available about the impact of many drugs on human spermatozoa. New approaches should be designed that more accurately reflect the findings in men, including more studies on human sperm in vitro and studies using other systems (ex vivo tissue culture, xenograft models, in silico studies, etc.). In addition, the present data is often incomplete or reported in a manner that prevents interpretation of their clinical relevance. Changes should be made to the requirements for pre-clinical testing, drug surveillance, and the warning labels of drugs to ensure that the potential risks to human fertility are clearly indicated.

Recent observations on drugs and human fertility

The transmembrane migration method has permitted quantification of the effect of drugs on human sperm motility. Calcium ionophores and calcium antagonists have paradoxical effects on motility depending on the stage of sperm maturity. Drugs with membrane stabilizing properties inhibit sperm motility. Propranolol, for example, has been shown to have contraceptive activity when administered intra-vaginally. Pharmacokinetic studies have shown that the systemic availability of vaginally administered propranolol is markedly greater than after oral administration. Seminal fluid concentrations of propranolol after oral administration are similar to those in plasma, but cervicovaginal mucus concentrations are much higher, and residence times much longer. The clinical consequences of these observations await elucidation.