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The Term “Potency”

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The Term “Potency”

Potency is a measure of drug activity expressed in terms of the amount required to produce an effect to given intensity. The more potent a drug the lower the amount required to produce the effect.

The term relative potency is used to express the biological activity of a sample preparation compared to a standard preparation.

In chapter 5.3 of the European Pharmacopoeia 2005 the following definitions for the term potency are given:

  • stated potency or labelled potency
    In the case of a formulated product a nominal value assigned from knowledge of the potency of the bulk material; in the case of bulk material the potency is estimated by the manufacturer.
  • assigned potency
    The potency of the standard preparation.
  • assumed potency
    The provisionally assigned potency of a preparation to be examined which forms the basis of calculating the doses that would be equipotent with the doses to be used of the standard preparation.
  • potency ratio
    The ratio of equipotent doses of the standard preparation and the unknown preparation under the conditions of the bioassay.
  • estimated potency
    The potency calculated from bioassay data.

Calculate the potency of a drug easily and safely with our PLA 3.0 bioassay software. The software features roughly 70 different tests and comes with options for equivalence margin development and control charts. PLA 3.0 is available as a fully functional trial version. Download it now.

Potency ratio–a brief synopsis

Affiliation

  • 1 Division of Endocrinology, Jewish Hospital of St Louis, MO 63110.
  • PMID: 8495276
  • DOI: 10.1093/rheumatology/32.suppl_2.24

Potency ratio–a brief synopsis

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Author

Affiliation

  • 1 Division of Endocrinology, Jewish Hospital of St Louis, MO 63110.
  • PMID: 8495276
  • DOI: 10.1093/rheumatology/32.suppl_2.24

Abstract

Deflazacort (DFZ) is a novel glucocorticoid with bone sparing properties, and there have been numerous studies investigating its potency relative to other glucocorticoids. As estimates of potency are difficult to evaluate in patients with disease, the concept of minimum effective dose is used. In double-blind, crossover studies, paired patient studies and between-patient studies, the potency of DFZ to prednisone (PDN) and to methylprednisolone was established as being 1.28:1 (1.17-1.38, 95% CI) and 1.6:1 (1.45-1.75, 95% CI), respectively. The bone wasting properties of DFZ have been determined using the concept of bone wasting ratio (ratio between bone loss velocity values observed in patients given the minimum effective doses of two glucocorticoids). The results of three studies which have evaluated the bone wasting ratio of PDN to DFZ indicate that this ratio is approximately 2.03:1 (1.84-2.23, 95% CI). That is, at therapeutically equivalent doses, twice as much bone loss occurs with PDN as with DFZ.

Deflazacort (DFZ) is a novel glucocorticoid with bone sparing properties, and there have been numerous studies investigating its potency relative to other glucocorticoids. As estimates of potency are difficult to evaluate in patients with disease, the concept of minimum effective dose is used. In do … ]]>