Prophylactic Usage
Safety and efficacy of prophylactic use of Griseofulvin Oral
Suspension has not been established.
Chronic feeding of griseofulvin, at levels ranging from 0.5-2.5% of the diet,
resulted in the development of liver tumors in several strains of mice,
particularly in males. Smaller particle sizes result in an enhanced effect.
Lower oral dosage levels have not been tested. Subcutaneous administration of
relatively small doses of griseofulvin once a week during the first three weeks
of life has also been reported to induce hepatomata in mice.Although studies in
other animal species have not yielded evidence of tumorigenicity, these studies
were not of adequate design to form a basis for conclusions in this regard.
In subacute toxicity studies, orally administered griseofulvin produced
hepatocellular necrosis in mice, but this has not been seen in other species.
Disturbances in porphyrin metabolism have been reported in griseofulvin-treated
laboratory animals. Griseofulvin has been reported to have a colchicine-like
effect on mitosis and cocarcinogenicity with methylcholanthrene in cutaneous
tumor induction in laboratory animals.
Reports of animal studies in the Soviet literature state that a griseofulvin
preparation was found to be embryotoxic and teratogenic on oral administration
to pregnant Wistar rats. Rat reproduction studies done in the United States and
Great Britain were inconclusive in this regard. Pups with abnormalities have
been reported in the litters of a few bitches treated with griseofulvin. Because
the potential for adverse effects on the human fetus cannot be ruled out,
additional contraceptive precautions should be taken during treatment with
griseofulvin and for a month after termination of treatment. Griseofulvin Oral
Suspension should not be prescribed to women intending to become pregnant within
one month following cessation of therapy.
Suppression of spermatogenesis has been reported to occur in rats but
investigation in man failed to confirm this. Griseofulvin interferes with
chromosomal distribution during cell division, causing aneuploidy in plant and
mammalian cells. These effects have been demonstrated in
vitro at concentrations that may be achieved in the serum with the
recommended therapeutic dosage.
Since griseofulvin has demonstrated harmful effects in
vitro on the genotype in bacteria, plants, and fungi, males should wait
at least six months after completing griseofulvin therapy before fathering a
child.