Drug Q&A

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(a) (i) An agonist is a drug that mimics a natural messenger and activates the associated receptor for that messenger. Nicotine is an agonist for the acetylcholine receptor. (ii) A competitive antagonist is an antagonist whose degree of antagonism is directly linked to the relative concentrations of the agonist and the antagonist. This indicates that both agonist and antagonist bind to the same site on the receptor or that the antagonist directly interferes with the binding of the agonist. This is a dose response curve illustrates the response to a competitive antagonist alone This is dose response curve of a competitive antagonist in the presence of an agonist (iii)A non-competitive antagonist is an antagonist whose action on the receptor is independent of the concentration of the agonist. This is because they bind at different sites in the receptor. This is a dose response curve for a non-competitive antagonist alone This is a dose response curve for a non-competitive antagonist in the presence of an agonist (b) Chemical Enhancers A variety of chemical additives have been investigated to enhance the penetration of transdermal delivery. These can be classified as solvents, surfactants, fatty acids/esters, and terpenes. These additives increase skin permeability by various mechanisms including increasing solubility and by creating an easier path through the stratum corneum. Iontopheresis Iontopheresis is a small electric field of low current which is applied to the skin at the area of drug application. The mechanism of this application is thought to be either electrophoresis or electrosmosis. This method has been shown to increase the penetration of the drug by orders of magnitude a... ... middle of paper ... ...eceptor occupancy reaches saturation. Compound C reaches a relatively lower response value of 40%, which is a typical result of a partial agonist. (iii) The statement cannot be proven with the information shown on the plot as compounds A and B are not being tested for affinity. (iv) The statement is partially correct. The response of compound A is 100% at very low concentrations which means it produces a maximal response; however this is not linked to receptor occupancy. We have no information about the occupancy/response relationship and full occupancy at all concentrations is impossible. Works Cited Lane, D. P. and P. M. Fischer. "Turning the key on p53." Nature 427.6977 (2004): 789-90. Prausnitz, M.R., Mitragotri, S. and Langer, R. (2004), ‘Current status and future potential of transdermal drug delivery’, Nature Reviews Drug Discovery, 3, pp.115–124.

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