Potency and effectiveness

What do the terms potency and effectiveness of a drug mean Explain the definitions of therapeutic index and safety margin. 

Thioridazine (Mellaril). The potency and effects of thioridazine are very similar to chlorpromazine. It should also be started at a relatively low dose and increased stepwise to help patients become adjusted to its effects. 

Note The last two steps give sympathomimetic substances as do all of the steps that follow. If the potency and effects of the DOM analogs are not important to you then you may stop after completing the second step (2,5-dimethoxyamphetamine). 

This is exemplified for MDA however, it may be replaced with any equimolar amount of any of the above propenylbenzenes to create the desired potency and effect, for instance, replacing... 

The potency and effectiveness of TAC have prompted studies to investigate withdrawal of corticosteroids or other concomitant immunosuppressants. A large randomized, controlled trial compared triple-drug therapy, consisting of TAC, corticosteroids, and mycophe-nolate mofetil, with early withdrawal of corticosteroids or mycophe-nolate in kidney transplant recipients. The results demonstrated equal efficacy in the three arms with no difference in acute rejection rates after 6 months of therapy. Furthermore, TAC has demonstrated equal efficacy to CSA, each in combination with azathioprine, with regard to corticosteroid withdrawal. ... 

Sosik, J. J., Avolio, B. J., and Kahai, S. S. (1997), Effects of Leadership Style and Anonymity on Group Potency and Effectiveness in a Group Decision Support System Environment, Journal of Applied Psychology, Vol. 82, pp. 89-103. 

The CnitedSfates Pharmacopeia (USP) and the Hationa/Pormu/aTy (NP) ate the recognized standards for potency and purity for most common dmg products. The USP was first pubflshed in 1833 the NP in 1887. Upon adoption of the first Pood and Dmg Act in 1906 these compendia became official, ie, they pubflsh the legal standards of quaUty, purity, and strength. The 1980 editions of USP(XX) and NP(XV) were combined for the first time revisions take place every five years. USPXXIII/NFXVIII is effective as of 1995. 

The natural compounds cortisol [50-23-7], cortisone [53-06-5], and corticosterone [50-22-6] vary only slightly in stmctures and pharmacologic properties (see Steroids). The synthetic analogues inmore modem practice, prednisolone [52438-85-4], dexamethasone [50-02-2], triamcinolone [124-94-7], and betamethasone have greater antiinflammatory potency, and their effects on sodium retention tend to be less severe. 

Phosphonylmethoxyethyl)adenine [106941-25-7] (PMEA, 65) (173), synthesized in 1987 (174), is foremost among the acycHc nucleoside analogues proven to be effective inhibitors of HIV-1 repHcation. The in vitro potency and selectivity of PMEA is comparable to the antiHIV-1 potency and selectivity of 2, 3 -dideoxy-adenosine (175). Although less potent than AZT in vitro PMEA, CgH22N 04P, is markedly more potent than AZT as an in vivo inhibitor of retrovims repHcation (176). In fact, PMEA has proven efficacious in the treatment of murine, feline, and simian retrovims infections in mice, cats, and monkeys, respectively. 

CarbocycHc 2/3 -didehydro-2/3 -dideoxyguanosine [118353-05-2] (carbovk, CBV, 66), C H 2N502, synthesized in 1988 (177), is a promising candidate for the chemotherapy of AIDS. CBV inhibits HIV repHcation and HIV-induced cytopathic effects in a variety of human T-lymphoblastoid ceU lines at concentrations approximately two hundred- to four hundredfold below its cytotoxic concentrations (177). CBV is as effective as AZT and DDC in reducing the expression of vkal antigen in HIV-infected CEM ceUs (177). The antivkal potency and selectivity of carbovk is comparable to the anti-HIV-1 potency and selectivity of 2/3 -dideoxyadenosine (178). The exact mode of antivkal action of carbovk has not yet been elucidated, but may be the modulating effect of intraceUular nucleotides on 5 -nucleotidase activity (179). 

Pesticides. Many pesticides are highly concentrated and are in a physical form requiring further treatment to permit effective appHcation. Typically carriers or diluents are used (see Insectcontroltechnology). Although these materials are usually considered inert, they have a vital bearing on the potency and efficiency of the dust or spray because the carrier may consist of up to 99% of the final formulation. The physical properties of the carrier or diluent are of great importance in the uniform dispersion, the retention of pesticide by the plant, and in the preservation of the toxicity of the pesticide. The carrier must not, for example, serve as a catalyst for any reaction of the pesticide that would alter its potency. 

The first idea to consider is the effect of receptor density on sensitivity of a functional system to agonists. Clearly, if quanta of stimulus are delivered to the stimulus-response mechanism of a cell per activated receptor the amount of the total stimulus will be directly proportional to the number of receptors activated. Figure 5.8 shows Gi-protein-mediated responses of melanophores transiently transfected with cDNA for human neuropeptide Y-l receptors. As can be seen from this figure, increasing receptor expression (transfection with increasing concentrations of receptor cDNA) causes an increased potency and maximal response to the neuropeptide Y agonist PYY. 

Receptor density has disparate effects on the potency and maximal responses to agonists. The operational model predicts that the EC50 to an agonist will vary with receptor density according to the following relationship (see Section 3.13.3)... 

Furchgott method, 92, 95, 97-98 G-protein coupling effects on, 76 partial, 89-91, 97, 124, 260-261 potency and, 80f Agonist occupancy, 115 Aikake s information criteria, 243, 243f Alleles, 6... 

Figure 4.5 Illustration ofthe concepts of potency that is, it is potent but not very effective. Inhibitor and effectiveness for two enzyme inhibitors. B shows less affinityfortheenzyme (high /<,), but Inhibitor A has a strong affinity for the enzyme it is a much more effective inhibitor when (low ff ), but even when it is maximally bound to maximally bound-that is, it is notvery potent but the enzyme it only achieves partial inhibition - is effective.

---