High-Throughput Dissolution/Permeation Screening —A 96-Well Two-Compartment Microplate Approach
Early formulation screening can alleviate development of advanced oral drug formulations, such as amorphous solid dispersions (ASDs). Traditionally, dissolution is used to predict ASD performance. Here, a high-throughput approach is described that simultaneously screens drug dissolution and permeation employing a two-compartment 96-well plate. Freeze-drying from hydro-alcoholic solutions was used to prepare amorphous formulations. The screening approach was tested on amorphous and crystalline tadalafil formulations with and without Soluplus®. The workflow consisted of: 1) dispersion of the formulations; 2) incubation within the two-compartment plate, where a dialysis membrane separated donor (dispersed formulation) and acceptor; 3) sampling (donor and acceptor), where donor samples were centrifuged to remove non-dissolved material; and 4) quantification by UHPLC-UV. To identify optimal screening conditions, the following parameters were varied: dispersion medium (buffer / biomimetic media), acceptor medium (buffer / surfactant solutions), and incubation time (1, 3, and 6 h). Surfactants (acceptor) increased tadalafil permeation. Biomimetic medium (donor) enhanced dissolution, but not permeation, except for freeze-dried tadalafil, for which the permeated amount increased. The predictiveness was evaluated by comparing dissolution-/permeation-results with in vivo bioavailability. In general, both dissolution and permeation reflected bioavailability, whereof the latter was a better predictor. High-throughput dissolution/permeation is regarded promising for formulation screening.
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Drug Permeability Profiling Using the Novel Permeapad® 96-Well Plate
Purpose Here,firstexperienceswithaprototypetoolforhigh throughput (passive) permeability profiling, a 96-well plate comprising the Permeapad® membrane, are reported. The permeabilities of a set of drugs were determined and compared to published measures of oral absorption, such as human fraction absorbed (Fa) and in vitro permeability values obtained using other tools.
Methods The tool consists of a 96-well bottom and screen plate with the artificial, phospholipid-based barrier (Permeapad®) mounted between the plates’ lower and upper compartments. The permeability of 14 model compounds including high- and low-absorption drugs, cationic, anionic, zwitterionic and neutral molecules, was determined by quantifying the compounds’ transport over time, deriving the steady-state flux from the linear part of the cumulative curves and calculating the apparent permeability (Papp). The membrane structure was investigated in a high-resolution digital light microscope.
Results The Permeapad® 96-well plate was found suited to distinguish high and low absorption drugs and yielded a hyperbolic correlation to Fa. The Papp values obtained were congruent with those determined with in-house prepared Permeapad® in the Franz cell set-up. Furthermore, good to excellent correlations were seen with Caco-2 permeability (R2 = 0.70) and PAMPA permeability (R2 =0.89). Microscopic investigation of the Permeapad® barrier
revealed the formation of phospholipid vesicles and myelin figures in aqueous environment.
Conclusion The Permeapad® 96-well plate permeation setup is a promising new tool for rapid and reproducible passive permeability profiling.
Springer Science+Business Media, LLC, part of Springer Nature 2020
Evaluating the influence of UWL and its composition on permeability profiling of two model drugs by using the PermeaPad®Plate and 2mag MIXdrive 96 MTP magnetic stirrer
New chemical entities (NCE) synthesized in pharmaceutical laboratories across the world must have desirable physicochemical characteristics like solubility, membrane/aqueous partition coefficient etc. (1) before they are investigated in in vitro permeability assays. These assays, as their name imply, will determine the apparent permeability of NCE and decide their further destiny as possible active pharmaceutical ingredients. Apparent permeability as molecule property is a composite of the membrane effect and the unstirred water layer (UWL) adjacent to both sides of the barrier. UWL, as stagnant layer, acts as diffusion barrier and rate-limiting factor for rapidly permeating, highly lipophilic drugs. For hydrophilic drugs, the velocity of permeation process will be determined by the permeability through the membrane since the membrane (not the UWL) is the slow step in permeation for such drugs. Many plate-basedin vitro assays report permeability in water instead the permeability of the membrane itself (2), leading to underestimation of the mitigating effect of UWL on permeability, which leads to poor correlation between experimental values and fraction absorbed (i.e. bioavailability) in humans. Although considerable effort has been put in developing new permeability models with various types of biomimetic barriers, the influence of the unstirred water layer (UWL) remains poorly studied in such assays. UWL is formed in close proximity of any barrier (biologic or artificial) due to insufficient/inefficient stirring, which leads to a concentration gradient between the bulk solution and the barrier. It is believed that UWL acts as an additional permeability barrier by reducing the net flux and, as a consequence, the apparent permeability coefficient (Papp) of drugs through a barrier.The aim of this work was to examine the contribution of UWL as an additional barrier on permeability of two model drugs –caffeine (CAF) and hydrocortisone (HC) using PermeaPad®96-well plate under different experimental conditions. CAF and HC are a water-soluble/highly permeable and a poorly soluble and medium/low permeable compound, respectively. Experiments were conducted with different ratesand types of agitation/stirring pH values and donor solutions with various API concentrations.