Abstract: The present review gives the details of the genotoxic
studies carried out till date for some selected synthetic progestins.
Mutagenicity is defined as a permanent change in content or structure
of the genetic material of an organism. A mutagenic hazard can be manifested
as a heritable change resulting from germ-line mutations and/or somatic
mutations leading to cancer or other chronic degenerative processes such
as aging. Reactive Oxygen Species (ROS) generated through normal metabolic
processes or from toxic products, can lead to a state of oxidative stress
that contributes to the pathogenesis of a number of human disease by damaging
lipids, protein and DNA. Oral contraceptives have been used since the
early 1960s and are now used by about 90 million women world wide. The
pill is given as a combination of an estrogen and a progestogen. The estrogen
component of combined oral contraceptives is either ethinylestradiol or
mestranol and the progestogens used are cyproterone acetate, desogestrol,
ethynodiol diacetate, levonorgestrel, lynestrenol, megestrol acetate,
norethisterone, norethisterone acetate, norethynodrel, norgestimate and
norgestrel. Little is known about the long term health risks and potential
protective effects of these individual components. Synthetic progestins
induced the genotoxic damage and also various types of cancers, both singly
as well as in combination with estrogens. Various synthetic progestins
have been tested for their genotoxic effects in different experimental
models, using different genotoxic end points. Ethynodioldiacetate, norethynodrel,
norgestrel, lynestrenol and medroxyprogesterone acetate were found to
be genotoxic only in the presence of metabolic activation supplemented
with NADP. Megestrol acetate, cyproterone acetate and chlormadinone acetate
were found to be genotoxic in the absence of metabolic activation. On
the basis of reports available it is suggested that the progestins in
which double bond between carbon-6 and carbon-7 is present, they undergo
nucleophilic reaction and generates free radical in the system to show
the genotoxic effects and the progestins in which double bond between
carbon-6 and carbon-7 is absent, they need metabolic activation like estrogens,
such as estradiol-17β and ethinylestradiol to show the genotoxic
effects. |