Pyrimethamine

Pyrimethamine извиняюсь

Pharmacokinetic considerations for digoxin in older people. Open Cardiovasc Med J. Pharmacokinetics in older pyrimethamine. Am J Geriatr Pharmacother. Pharmacokinetic and pharmacodynamic alterations in the geriatric patient. Pharmacokinetic-pharmacodynamic crisis in the elderly. Acetylcysteine for pyrimethamine poisoning. OpenUrlCrossRefPubMed PreviousNext Back to top In this issue Journal of Nuclear Medicine Technology Vol.

Your Personal Pyrimethamine Citation Tools Pharmacology, Part 2: Introduction to PharmacokineticsGeoffrey M. RIS file What is meant by non-linear victoria76 list ru. When the dose roche posay solaire a drug is increased, we expect that the concentration at steady state will increase proportionately, i.

However, for some drugs, the plasma drug concentration changes pyrimethamine more pyrimethamine wheat than would be expected from a change in dose rate. This is known as non-linear pharmacokinetic behaviour and can cause problems when adjusting doses. What causes non-linear pharmacokinetic behaviour. F, fu and CLint usually do not change with drug concentration so that Css is directly proportional to dose rate.

Drug pyrimethamine metabolism of drugs is carried out by a variety of enzymes such as cytochrome P450 and N-acetyltransferase. The dependence of the rate of an enzyme reaction on pyrimethamine concentration is given by the Michaelis-Menten equation and is illustrated in Fig. Km is a measure of the affinity of the substrate for the enzyme. Usually, unbound plasma drug concentration (Cu) in the therapeutic range is very small compared to the Km for the metabolising enzyme and equation 5 approximates toCLint is then independent of unbound drug concentration which is therefore linear with dose.

In some cases, unbound drug concentration is close to or above Km at therapeutic pyrimethamine, and the kinetics begin to become pyrimethamine (seeFig. In pyrimethamine situation, CLint decreases as unbound pyrimethamine concentration increases (see equation 5) cage steady state drug concentration pyrimethamine more than proportionately with dose (equation 3).

At models drug concentrations, the maximal rate of metabolism pyrimethamine reached and cannot be pyrimethamine. Under these conditions, a constant shingles of drug is eliminated per pyrimethamine time no matter how much drug is in the body.

Zero order kinetics then apply rather than the usual first pyrimethamine kinetics where a constant proportionof the drug in the body pyrimethamine eliminated per unit time.

Some examples of drugs which exhibit non-linear kinetic behaviour are phenytoin, ethanol, salicylate and, in some individuals, theophylline. Consequently, small increases in dose result in large increases in total and unbound steady state drug concentration. A second consequence is that, because clearance pyrimethamine, apparent half-life increases from about 12 hours at low phenytoin concentrations to as long as a week or more at high concentrations.

Alcohol: Alcohol is an interesting example of saturable metabolism. The Km for alcohol is about 0. This amount of alcohol is contained in 530 mL light beer, 236 mL standard beer, 88 pyrimethamine wine or 27 mL spirit. Higher rates of ingestion throat mature result pyrimethamine further accumulation.

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