Objective of pharmacovigilance
The objective of pharmacovigilance is the reduction of the frequency and the severity of adverse effects of drugs while maintaining or, better, improving their efficacy. The adverse effect of a drug should not be considered without taking account of its beneficial effects.
The conditions necessary to achieve this goal are the quality of drugs, a good knowledge of their properties and of the particularities of the patient.
The quality of drugs more particularly depends on the pharmaceutical industry and the authorities responsible for their approval on the market and their withdrawal if necessary and the recommendations for their use.
The prescriber must be particularly informed of adverse effects of the drugs that he prescribes. The pharmacist who dispenses drugs must detect errors of prescription, possible interactions between drugs. But all the people are concerned, dentists, nurses, midwife and the patients themselves.
An exact diagnosis does not guarantee a good treatment, but an incorrect diagnosis will lead to an inappropriate or dangerous treatment. The diagnosis does take into account the current disease of the patient but also his general condition and his particularities, renal failure, advanced age, pregnancy. The existence of renal impairment must lead to a diminution of the dosage of drugs with predominant renal elimination. T he majority of adverse effects of drugs occur in elderly of more than 60 years; this high frequency can be explained by their different disorders and by the use of a lot of drugs for trying to correct these disorders.
Pregnancy is a particular situation. Since, in particular, the unhappy experiments of thalidomide and diethylstilbestrol, we know that drugs even little toxic for adults can, when they are taken by pregnant women, induce serious malformations in the neonates (teratogenic action) or delayed disorders. Thalidomide is a sedative which, prescribed to pregnant women in Germany , induced in neonates malformations called phocomelia (defective development of arms and legs). Diethylstilbestrol is a synthetic estrogen which, prescribed to pregnant women for preventing a premature delivery (it was inactive in this indication!) induced cancers of the vagina in the 15 to 20 years old girls born from treated mothers.
The teratogenic effect of a drug is highest during the first three months of pregnancy, except the first ten days after conception where if it is toxic for the fetus it causes an abortion .
A non teratogenic drug taken during the second or third trimester of pregnancy can induce disorders in the child, for example ACE (angiotensin converting enzyme) inhibitors can give oligohydramnios, growth retardation, renal insufficiency and even dead. Ace inhibitors should be avoided throughout pregnancy.
When prescribing a drug to a woman in child bearing age, the doctor must question about a possible pregnancy. If a prescription is necessary, he should choose in the therapeutic class he is intended to prescribe an old drug which has been already frequently used by pregnant women without adverse effects.