Considerable efforts have been made to develop a male contraceptive and the studies have provided very useful infor-mation in this field. At least five different strategies to develop a male contraceptive have been pu...Considerable efforts have been made to develop a male contraceptive and the studies have provided very useful infor-mation in this field. At least five different strategies to develop a male contraceptive have been pursued, namely: inhi-bition of sperm production, interference with sperm function, interruption of sperm transport, prevention of sperm de-position, and prevention of sperm-egg interaction. Of all these approaches, inhibition of sperm production by using an-drogens either alone or in combination with progestins have given the most encouraging results. A nmnber of clinicaltrials substantiate that it is indeed possible to have a reversible, effective and safe hormonal method of contraception. Apostmeiotic and epididymal approach to interfere with sperm function or the secretory and metabolic processes of theepididymis is another attractive option of male contraceptive development. A number of chemical compounds have beenidentified which interfere with sperm function in the epididymis without affecting sperm production, however, the com-pounds evaluated so far were found to be toxic. Interruption of sperm transport through the vas either by vasectomy orpercutaneous intmvasal injection of liquids which form cure-in-place plugs is also an attractive option. However, re-versibility of the methods is of concern in their wide scale use. The major constraint in developing a long-acting male contraceptive seems to be the need for greater investment forproduct development. The clinical trials for evaluating the efficacy and safety of the new products and formulationsstretch over several years and require enormous financial commitment. Nevertheless, the long-term gain of having along-acting reversible contraceptive for men is far greater than the financial commitments over few years. Male attitudetowards using methods of family planning is much more favourable than originally believed. The pharmaceutical indus-try as well as the health care providers therefore have a greater responsibility. For early development of a contraceptivefor men, it is essential to increase investment and simplify the drug regulatory procedures. The advent of newer tech-nologies coupled with the convergent efforts of scientists will certainly make it possible to have an effective, safe andreversible male contraceptive in the near future.展开更多
Nineteen L-N-2-hydroxyethylamino acids and L-N,N-bis(2-hydroxyethyl)amino acids were prepared from the reaction of chlorohydrin with L-alanine,L-valine,L-leucine,L-isoleucine,L- phenylalanine,L-serine,L-thrcunine,L-gl...Nineteen L-N-2-hydroxyethylamino acids and L-N,N-bis(2-hydroxyethyl)amino acids were prepared from the reaction of chlorohydrin with L-alanine,L-valine,L-leucine,L-isoleucine,L- phenylalanine,L-serine,L-thrcunine,L-glutamic acid,L-aspartic acid and glycine.L-N,N,N',N'-tetra (2-hydroxyethyl)cystine was prepared by the reaction of L-cystine with chlorohydrin.展开更多
文摘Considerable efforts have been made to develop a male contraceptive and the studies have provided very useful infor-mation in this field. At least five different strategies to develop a male contraceptive have been pursued, namely: inhi-bition of sperm production, interference with sperm function, interruption of sperm transport, prevention of sperm de-position, and prevention of sperm-egg interaction. Of all these approaches, inhibition of sperm production by using an-drogens either alone or in combination with progestins have given the most encouraging results. A nmnber of clinicaltrials substantiate that it is indeed possible to have a reversible, effective and safe hormonal method of contraception. Apostmeiotic and epididymal approach to interfere with sperm function or the secretory and metabolic processes of theepididymis is another attractive option of male contraceptive development. A number of chemical compounds have beenidentified which interfere with sperm function in the epididymis without affecting sperm production, however, the com-pounds evaluated so far were found to be toxic. Interruption of sperm transport through the vas either by vasectomy orpercutaneous intmvasal injection of liquids which form cure-in-place plugs is also an attractive option. However, re-versibility of the methods is of concern in their wide scale use. The major constraint in developing a long-acting male contraceptive seems to be the need for greater investment forproduct development. The clinical trials for evaluating the efficacy and safety of the new products and formulationsstretch over several years and require enormous financial commitment. Nevertheless, the long-term gain of having along-acting reversible contraceptive for men is far greater than the financial commitments over few years. Male attitudetowards using methods of family planning is much more favourable than originally believed. The pharmaceutical indus-try as well as the health care providers therefore have a greater responsibility. For early development of a contraceptivefor men, it is essential to increase investment and simplify the drug regulatory procedures. The advent of newer tech-nologies coupled with the convergent efforts of scientists will certainly make it possible to have an effective, safe andreversible male contraceptive in the near future.
文摘Nineteen L-N-2-hydroxyethylamino acids and L-N,N-bis(2-hydroxyethyl)amino acids were prepared from the reaction of chlorohydrin with L-alanine,L-valine,L-leucine,L-isoleucine,L- phenylalanine,L-serine,L-thrcunine,L-glutamic acid,L-aspartic acid and glycine.L-N,N,N',N'-tetra (2-hydroxyethyl)cystine was prepared by the reaction of L-cystine with chlorohydrin.
