Calculation of the blood level of a drug taken orally with a diffusion controlled dosage form

Assessment of antibiotic levels in lung tissue with erosion-controlled dosage forms

“…As already shown in previous studies, it is possible to determine the drug level in the blood compartment associated with controlled release dosage forms taken orally (22,23), and the effect of dose frequency appeared to be a significant parameter (24). The previous model has been extended to transfer into the lung tissue with this type of dosage form,…”

“…Another approach was developed based on numerical models taking into account all the available data, e.g. the kinetics of drug release in the gastrointestine (01), the stages of absorption in the blood compartment and elimination (22)(23)(24)(25). Following this approach, another numerical model with finite differences was built, taking into account the following stages: drug release in the GI tract, absorption in the blood compartment and elimination, and transient diffusion from the blood compartment into the lung tissue.…”

Calculation of the antibiotic level in the lung tissue and bronchial secretion with an oral controlled-release dosage form

“…This problem was resolved by building a numerical model taking the following facts into account: the kinetics of drug release in the gastrointestinal tract, which is generally determined using in-vitro tests; the stage of absorption in the blood compartment and the stage of elimination. This model was successfully tested in various cases in previous papers [20], and the authors were able not only to predict the drug level in the blood obtained with controlled-release dosage forms but also to determine the effect of parameters of interest, such as the dose frequency [21] and the gastrointestinal tract time [22]. The model is described in the section on Theoretical considerations.…”

“…It is possible to calculate the concentration-time histories of ciprofloxacin after taking a controlled-release dosage form, not only in the serum [20][21][22], but also in other parts of the body such as blister fluid [24]. By using the numerical model described in this paper, the concentration-time histories of ciprofloxacin were calculated and drawn in the following places: serum (1), serum-lung tissue interface (2), mean value in the lung tissue (3), lung tissue-bronchial secretion interface (4) and bronchial secretion (5) with dosage forms in which drug release is controlled by erosion.…”

“…This is why the Food and Drug Administration (FDA) have conducted studie for establishing in-vitro/in-vivo correlation by means of two workshops [16,17[ However, these correlations were found not able "to provide meaningful data at th~ time" [18] and three levels of correlation were defined [19]. Another approach was t build numerical models taking all the known facts into account, namely the kinetics ( drug release from the dosage form, whatever the process of drug release, and tl~ following stages of absorption into, and elimination from, the plasma compartmel [20]. Further studies along these lines provided evidence that two factors, tt gastrointestinal (GI) tract time [21] and the dose frequency [22], should be consider~ in these numerical models.…”