[Therapeutic equivalence and inequivalence of chemically identical substances using cardiac glycosides for an example (author's transpl)].

The problem of therapeutic equivalence or inequivalence cannot be solved by "ignoring facts and proclaiming opinions". The entire problem is multifarious and is not even clearly arranged although heart glycosides have been used for 200 years in the therapy of cardiac insufficiency. It comprises the physico-chemical properties of the drugs, its preparation and its pharmacolinetic behaviour in the organism. Therapeutic equivalence or inequivalence can primarily only be evaluated in connection with the disease and the symptoms of disease, respectively. Thus, manufacturers, pharmacists and physicians likewise are confronted with the problem. The differences in bioavailability of the individual cardiac glycosides show the necessity for: 1. The number of fixed combinations of heart glycosides should be limited in the interest of drug safety. 2. Only such drugs should be approved whose quantitative and qualitative equivalence has been demonstrated with regard to the monoglycoside. 3. When prescribing digoxin derivatives one should not only observe the bioavailability but take also into account the chemical stability and the pharmacolinetic behaviour.