11/9/2022 0 Comments Volume of distribution![]() ![]() Two postdistribution vancomycin concentrations are needed to accurately determine patient-specific pharmacokinetic parameters, estimate area under the curve, and improve the precision of vancomycin dosing in this patient population.īayesian body mass index glycopeptide morbid obesity pharmacokinetics vancomycin administration and dosage. Results of the largest analysis of vancomycin V in class III obesity to date indicated that use of a fixed V value (75 L) and use of a TBW-based estimate (0.52 L/kg) for estimation of vancomycin V in patients with a BMI of ≥40.0 kg/m2 have similar bias. A fixed estimate of V (75 L) and use of a weight-based value (0.52 L/kg by total body weight ) yielded similar bias and error in this population. ![]() V was lower in patients with a BMI of 40.0-49.9 kg/m2 than in those with a BMI of ≥50.0 kg/m2 (72.4 ± 19.6 L versus 79.3 ± 20.6 L, p = 0.009) however, body size poorly predicted V in regression analyses (R2 < 0.20). The median (5th, 95th percentile) weight of patients was 136 (103, 204) kg, and baseline characteristics were similar between BMI groups. Mean bias and root-mean-square error (RMSE) were calculated to assess the precision of multiple methods of estimating V. The relationship between V and body weight was assessed using linear regression. Individual pharmacokinetic parameter estimates were obtained via maximum a posteriori Bayesian analysis. highly protein bound drugs)Įffects of apparatus (e.g.To compare methods of estimating vancomycin volume of distribution (V) in adults with class III obesity.Ī retrospective, multicenter pharmacokinetic analysis of adults treated with vancomycin and monitored through measurement of peak and trough concentrations was performed. Measurement and pharmacokinetic modelling of V Dįree vs. Main factors which influence the apparent volume of distribution Category V D varies with individual height and weight, as well as accumulation of fat (for obese patients administered lipid-soluble drugs) or accumulation of fluids (in ascites, oedema or pleural effusion). V area – V D extrapolated from the AUC of the concentration curve.V extrap – V D of the tissue compartment (from the elimination phase).V initial – V D of the central compartment (from the rapid distribution phase).For V D larger than 42L, the drug is thought to be distributed to all tissues in the body.ĭepending on the timing of the observed plasma concentration, there are several types of volumes of distribution: Those with V D between 4 and 7L are thought to be distributed throughout the blood (plasma and red blood cells). This is clinically important when peak plasma concentration is essential for the therapeutic effectĭrugs with a volume of distribution of 4L or less are thought to be confined to the plasma. Variation of V D mainly affects the peak plasma concentration of the drug. V D is expressed in L or indexed to body mass in L/Kg. Properties like AUC and AUMC can also be. The above ratio assumes that the distribution of the drug between the tissues and the plasma is at equilibrium. Steady state volume of distribution: VssMRT×CL Half-life: Terminal slope of the natural log of the data. V D = Total amount of drug in the body / Drug blood plasma concentration Once a drug enters into systemic circulation by absorption. Volume of distribution is the apparent volume into which a drug disperses in order to produce the observed plasma concentration and has the following formula: Distribution is the process by which medication is dispersed throughout the body via the bloodstream. The volume of distribution (V D), also known as the apparent volume of distribution is a theoretical value (because the V D is not a physical space but a dilution space) that is calculated and used clinically to determine the loading dose that is required to achieve a desired blood concentration of a drug. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |