Drugs antagonists

Arunlakshana O, Schild HO (1959) Some quantitative uses of drug antagonists. Br J Pharmacol Chemother 14 48-58 Burnstock G, Cocks T, Crowe R, Kasakov L (1978) Purinergic innervation of the guinea pig urinary bladder. Br J Pharmacol 63 125-138... 

Catecholamines exert their effects through specific receptors on the target cell surface. However, the effects elicited depend on the type or subtype of receptor with which they interact. There are three types of catecholamine receptor dopamine, a-adrenergic, and )S-adrenergic. Each of these consists of at least two or more subtypes, which differ with respect to ligand affinity, tissue distribution, postreceptor events, and drug antagonists (Table 32-3). 

Figure 1. Ionic concentrations and equilibrium potentials for Na", and Ca " and the effects of drugs [ antagonist/agonists ] that regulate the ion channels.

Bacterial resistance to sulfonamides can originate by random mutation and selection or by plasmid transfer of resistance it usually does not confer cross-resistance to other classes of antibiotics. Resistance to sulfonamide results from altered constitution of the bacterial cell that causes (I) a lower affinity for sulfonamides by dihydropteroate synthase, (2) decreased bacterial permeability or active efflux of the drug, (3) an alternative metabolic pathway for synthesis of an essential metabolite, or (4) an increased production of an essential metabolite or drug antagonist. Plasmid-mediated resistance is due to plasmid-encoded, drug-resistant dihydropteroate synthetase. 

I Clinically useful drug antagonists are flutamide (an androgen-receptor blocker used to treat prostate i cancer), leuprolide (a GnRH analog used to treat prostate cancer), and finasteride (a 5-a-reductase I inhibitor used to treat benign prostatic hyperplasia and male pattern baldness). 

Maletzky BM. enelzine as a stimulant drug antagonist a preliminary repeat IntJAddict (1977)12,651-5. 

Contraceptives Anticancer agents Drug antagonists Other drugs, in general Sugars and polysaccharides Cells... 

---