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The minimum inhibitory concentration (MIC) and minimum bactericidal concentration are used to measure in vitro activity of antimicrobial agents. They are good indicators of antimicrobial potency, but don't give any information relating to time-dependent antimicrobial killing (the so-called post antibiotic effect).
For example, gentamicin is an antibiotic that can be nephrotoxic (kidney damaging) and ototoxic (hearing damaging); measurement of gentamicin through concentrations in a patient's plasma and calculation of the AUC is used to guide the dosage of this drug. [3] AUC becomes useful for knowing the average concentration over a time interval, AUC/t.
For example, the concentration in other areas may be approximately related by known, constant factors to the blood plasma concentration. In this one-compartment model, the most common model of elimination is first order kinetics , where the elimination of the drug is directly proportional to the drug's concentration in the organism.
Depending on the pathogen and antibiotics being tested, the media can be changed and/or adjusted. The antimicrobial concentration is adjusted into the correct concentration by mixing stock antimicrobial with media. The adjusted antimicrobial is serially diluted into multiple tubes (or wells) to obtain a gradient. The dilution rate can be ...
From the above definitions it follows that is the first derivative of concentration with respect to time, i.e. the change in concentration with time. It is derived from a mass balance. Clearance of a substance is sometimes expressed as the inverse of the time constant that describes its removal rate from the body divided by its volume of ...
The fraction of bound receptors is known as occupancy. The relationship between occupancy and pharmacological response is usually non-linear. This explains the so-called receptor reserve phenomenon i.e. the concentration producing 50% occupancy is typically higher than the concentration producing 50% of maximum response. More precisely ...
Ampicillin is a time-dependent antibiotic. Its bacterial killing is largely related to the time that drug concentrations in the body remain above the minimum inhibitory concentration (MIC). The duration of exposure will thus correspond to how much bacterial killing will occur.
Half maximal inhibitory concentration (IC 50) is a measure of the potency of a substance in inhibiting a specific biological or biochemical function. IC 50 is a quantitative measure that indicates how much of a particular inhibitory substance (e.g. drug) is needed to inhibit, in vitro , a given biological process or biological component by 50% ...