Drugs potency

Log normal distribution, the distribution of a sample that is normal only when plotted on a logarithmic scale. The most prevalent cases in pharmacology refer to drug potencies (agonist and/or antagonist) that are estimated from semilogarithmic dose-response curves. All parametric statistical tests on these must be performed on their logarithmic counterparts, specifically their expression as a value on the p scale (-log values) see Chapter 1.11.2. 

J.W. McFarland, On the parabolic relationship between drug potency and hydrophobicity. J. Med. Chem., 13 (1970) 1192-1196. 

These results clearly demonstrate that PCP-like drugs administered centrally produce stereotyped behavior that is mediated by PCP receptors. A causal relationship between binding to PCP receptors and induction of stereotyped behavior is also supported by the ability of metaphit, which specifically acylates PCP receptors in vivo, to antagonize induction of stereotyped behavior. The order of drug potency of PCP analogs and dexoxadrol to induce stereotyped behavior is similar to that seen in other studies on the binding of 3H-PCP (Hampton et al. 1982 Murray and Leid 1984) and... 

A number of recent publications indicate that the antibacterial field has adopted the concept of comparing free drug concentration at the site of action to in vitro drug potency reported as MIC [24-26]. A study of the antibacterial ertapenem in healthy volunteers was carried out to provide support for its use in skin and skin-structure infections [27]. Using microdialysis techniques, unbound drug concentrations in muscle and subcutaneous tissues were sampled at... 

The curve is identical to the first but the axes are labelled differently with percentage of maximum response on the y axis. This graph will have been produced from a functional assay in the laboratory on a single subject and is concerned with drug potency. Demonstrate that the EC50 is as shown. 

Drug potency Daily dose (mg) Dose/day Duration of action (h) Metabolism and excretion... 

These relationships have been useful to a certain extent as the basis for rational methods of drug design (24), and have been valuable also as probes for assessing which molecular properties are actually involved in determining drug potency and toxicity (23). ... 

VALIDATION PRACTICES Table 2.1. Guidelines for Drug Potency Assay... 

Potency is the dose of drug required to produce a specific effect of given intensity as compared to a standard reference. Potency is a comparative rather than an absolute expression of drug activity. Drug potency depends on both affinity and efficacy. Thus, two agonists can be equipotent, but have different intrinsic efficacies with compensating differences in affinity (IUPAC). 

Determination of drug potency in the presence of other emulsion components may require development of special analytical techniques for example, oils may interfere with standard reverse phase HPLC assays, requiring extraction techniques or the development of normal phase assays. Similarly, bioassays may give erroneous results when the drug is presented in an emulsion form. Hence, adequate controls and/or extraction techniques must be developed to give reliable values from the bioassay. 

Figure 8 is a plot of mean assay results for active ingredient Bl. Drug potency (200 mg per tablet) is measured in duplicate from samples obtained by grinding a composite of 20 randomly selected tablets. Figure 8 is also influenced by the variability of the purity of the raw material, which ranged from 97.6-99.5%. 

These potential effects are impacted by such factors as circumstances of use (e.g., medical use supervised by medical professionals versus abuse), dosage, and route of administration. In general, effects increase as drug potency increases. The onset of these effects ranges from an immediate response to the drug to the user experiencing the impact 30-60 minutes later. The duration of their effects lasts from three to seven hours. 

---