By present time the significant experience, testifying that many drugs can render adverse influence on a developing foetus and the newborn is saved up. The parity of a degree of risk with potential advantage of purpose of preparations is the basic problem of pharmacotherapy at pregnancy.
The majority of drugs get to a foetus quickly enough. In the end of gestagenic period at a foetus the basic biological systems start to function and the drugs can cause pharmacological effect peculiar to them.
Distinguish three pathological variants of action of drugs on a foetus:
1.embryotoxic;
2.teratogenic;
3.phetatocsic.
Embryotoxic action consists in negative influence of drugs substance on a zygote and blastosyst, being in a gleam fallopian pipes or in a cavity of a uterus. More often result is formation of rough developmental anomalies that lead to interruption of pregnancy. I.I.Ivanov and O.S.Sevostyanov mark that teratogenic (teratos - the ugly creature) action of drugs represent the greatest danger as lead to development of congenital anomalies in a foetus. Phetatocsic action is shown in closing natural apertures of a foetus, development genesis, a hydrocephaly and specific damages of bodies.
It is established, that at pregnancy there is a number of features of the exchange concerning both mothers, and a foetus and capable to influence pharmacokinetics of drugs.
For pregnant women it is characteristic “ physiological hypervolemia ”, retching maximum in 29-32 weeks. Concentration of preparation in a drug of volume decreases, and the useful effect decreases, and the increase in a doze of accepted drugs raises risk of occurrence of pathologies of a foetus.