Pharmacokinetics Language English Format: PDF Price - Tutorsindia

PharmacokineticsMultiple dosing76Conc (mg/L)5432FastSlow100 10 20 30 40 50 60 70 80Time (h)Figure 10.8 Fast and slow release dosage forms of the same dose of the same drugWith the fast release form, we get the same high, early peak as with single dosing and then once absorption has beenlargely completed there follows a fairly long period of elimination allowing a large drop in concentrations. The slow releaseform gives peaks that are later and lower, and there is now a shorter period of decline, so we do not see the low troughswe got with the other preparation. Slow release preparations can very effectively reduce fluctuations in concentration(They aren’t just a marketing gimmick!).10.6.4 Practical steps to restrict fluctuationFor any given drug there is little we can do about its half-life, but dose division and dosage form are within our control. Ifa drug has a rather short half life and we need to control concentration fluctuations we could achieve this in two differentways. The two traces in Figure 10.9 model the same total daily dose of drug, but in one case (solid line) we have suppressedfluctuation by giving the drug four times daily and in the other (dotted line) we have used a slow release form and onlyneeded to give the drug twice per day.25Conc (mg/L)201510Fast –50mg fourtimes dailySlow –100mgtwice daily500 10 20 30 40 50 60 70 80Time (h)Figure 10.9 Control of fluctuation in concentrations by either extreme dose division (solid line) or by using a slow release formulation (dottedline) in place of one with fast release.106Download free ebooks at bookboon.com