LD 50/ ED 50 is ?: (A) Therapeutic index, (B) Bioavailability, (C) Potency, (D) Efficacy
Answer is A. Ans. is 'a' i.e., Therapeutic index Therapeutic index Drugs usually have more than one action. The maximal response for different action of a drug may be different ie the DRCs (Dose response curves) for different effects of a drug may be different. The extent of separation of DRCs of a drug for different effects is a measure of its selectivity, e.g. the DRCs for bronchodilatation and cardiac stimulation are quite similar in case of isoprenaline but far apa in case of salbutamol - the latter is more selective. The gap between the therapeutic effect DRC and the adverse effect DRC defines the safety margin or the therapeutic index.