Half-life of drug

However, in many cases this will be a much to elaborate, expensive and time-consuming process to answer either very simple questions what is the half-life of drug Y ) or questions of a more general character (what are the current guidelines for the treatment of hypertension ). If so, there are many secondary sources of drug information, all of which contain information from the primary sources in a processed format, and all which have their different advantages and draw-backs (Table 1). 

Daily fluoxetine (Prozac) Long half-life of drug and risk of producing excessive CNS stimulation, sleep disturbances, and increasing agitation. Safer alternatives exist. High... 

The number of patients not yet relapsed versus time was plotted in Figure 5-6 to address the question of whether recurrence occurred at a constant or varying rate. When the data for % long-term placebo treatment were analyzed, relapses tended to occur along an exponential function analogous to that seen with the half-life of drugs in plasma (211). This indicates that relapse occurs at a constant rate. 

Oxidation drugs 1 Clearance and half-life of drugs with high extraction ratio... 

As with the situation in mammals, wide variations exist among avian species in the half-life of drugs that are primarily eliminated by hepatic biotransformation.The half-life of antimicrobial agents is prolonged in poikilothermic species (fish and reptiles), which is consistent with their much lower metabolic turnover rate, and is influenced by ambient (in the case of fish, water) temperature (Table 12). The rate of drug elimination increases (i.e., half-life decreases) with increase in ambient temperature and varies among fish species. 

Species variations in the half-life of drugs that are eliminated by renal excretion is less pronounced than for lipid-soluble drugs that undergo extensive hepatic biotransformation. The half-life of gentamicin, which is eliminated solely by glomerular filtration, is 0.5-1 h in laboratory animals, 1.25-2.5 h in domestic animals. 

Answer The half life of drug C is 1 hour (300 mg to 150 mg in 1 hour). After another half life, there will be... 

It is also apparent that the efflux of drug from the tissue and retention in tissue is dependent on the fraction unbound in tissue and in the blood and on blood flow rate. Consequently, Roberts and Cross (1999) showed that the half-life of drugs retained in tissues (Igs = 0.693/ ,) could be related to the ratio of the fraction of drug unbound in the plasma and tissue (Figure 13.8). A number of other compart-mental and diffusion models have been described and summarized (McCarley and Bunge, 2001 Anissimov and Roberts, 2004). 

Figure 10.20 Rowland and Tozer method. Data from Table 10.4 is plotted. (Cp)ss - (Cp)obs/ the difference between plasma concentration at steady state and that observed during the infusion, fi/2, half life of drug K, elimination constant. See text for further details.

S. Nakagawa and T. Mayumi, The use of PVP as a polymeric carrier to improve the plasma half-life of drugs. Biomaterials, 25, 3259-3266 (2004). 

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