Franz cells

Basket, paddle, or reciprocating cylinder with glass beads Paddle over disk Franz cell diffusion system Paddle, modified basket, or dual chamber flow-through cell Special apparatus [European Pharmacopoeia (PhEur)] Flow-through cell (powder/granule sample cell)... 

N. Leveque, S. Makki, J. Hadgraft, and P. Humbert. Comparison of Franz cells and microdialysis for assessing salicylic acid penetration through human skin. Int. J. Pharm. 269 323-328 (2004). 

For in vitro testing the Organisation for Economic Cooperation and Development (OECD) approved in 2004 test guideline 428 [37], which currently advocates the use of human, rat, and pig skin to measure cutaneous absorption by a vertical diffusion system (Franz cell). Dmg concentrations are followed in an acceptor fluid separated by the skin from the donor vehicle, which is applied to the external surface of the skin. Instead of human or animal skin, human skin models could be used as soon as the equivalence of their results are proven. Comparative studies indicate a correlation of penetration data in vitro and in humans [38]. 

Li, J. B. and P. C. Rahn. "Automated Dissolution Testing of Topical Drug Formulations Using Franz Cells and HPLC Analysis, Pharmaceutical Technology 17(71 44-52, 1993. 

Fig. 8 Cumulative amounts of TS ( ) and TSBH ( ) crossing isolated human skin tissue in Franz cells (n — 6). TS was applied as a 10% suspension. TSBH was applied as a 10% solution. In each case, the vehicle was pH 7.4 phosphate buffer (0.2 M). (From Ref > . )...

Most studies today are conducted in one-chamber diffusion cells that hold receptor fluid beneath the skin. The top surface of the skin is exposed to the environment and is surroimded by a short wall. A tube extends upward from the receptor fluid for manual sample removal. The Franz cell is the most widely known cell of this type (Franz, 1975). A flow-through diffusion cell (Figure 2.1) is a modification of this design that should have a much smaller receptor fluid chamber to permit easy removal of contents with a moderate flow (1 to 2 ml/h) of receptor fluid (Bronaugh and Stewart, 1985). The continual replacement of the receptor fluid pomits maintenance of skin viability when a physiological buffer is used (Collier etal., 1989). This diffusion cell also has the advantage of automatic samphng with the use of a fraction collector. 

Figure 2. Cumulative amount of gentamicin released from the eongilex "nonwoven PAN - gentamicin" obtained by chemisolptiaa (Franz cell)...

Hexosomes prepared by vortexing an ethanolic GMO/OA solution in an aqueous solution of PX188 and formulated as a carbomer gel have been proposed for the buccal delivery of progesterone. A much higher flux over excised buccal rabbit mucosa was observed in Franz-cell diffusion studies from the hexosome-containing formulation as compared to a progesterone... 

In summary, skin penetration tests consist of placing the piece of skin in a diffusion chamber (e.g., Franz-cell-type static diffusion chamber or flow-through diffusion cell) with two compartments. The external side of the skin is turned toward the upper compartment in which the test solution is applied. After a defined contact time with the skin surface, the effect of the surfactant on skin permeability properties is determined, often by means of a penetration marker (e.g., tritiated water). Many variations in penetration studies have been described and the reader is referred to other articles for more details [34,35]. 

M. -J. Lucero, C. Claro, M. Casas and M.-R. Jim nez-Castellanos, Drug diffusion from disperse systems with a hydrophobically modified polysaccharide Enhancer vs Franz cells, Carbohydr. Polym., 92 (1) 149-156, 2013. 

Fig. 7 Release profile of atenolol from the hydrogel C934-atenolol in a Franz cell against water black square) or NaCl solution black circle) as receptor media. Data adapted from reference [16])...

F. Netzlaff, K.-H. Kostka, C.-M. Lehr, and U. F. Schaefer. TEWL measurements as a routine method for evaluating the integrity of epidermis sheets in static Franz type diffusion cells in vitro. Limitations shown by transport data testing. Em J. Pharm. Biopharm. 63 44—50 (2006). 

While Franz-type diffusion cells are commonly used to assess in vitro penetration of compounds across the skin, they have also been used for the assessment of compound permeability across the buccal mucosa [19, 71, 104], In this system, buccal mucosa is sandwiched between two chambers, and compound solution is added to the donor chamber with compound-free buffer in the receptor chamber. The receptor chamber is then periodically sampled to assess the amount of compound that has permeated the tissue over time. 

Corresponding Papp value for atenolol and caffeine across freshly isolated human buccal mucosa mounted in Franz-type cell is 1.16 (0.25) and 14.5 (1.6), respectively. 

In many cases, transdermal drug absorption is investigated using a Franz-diffusion cell. The concentrations both in the membrane and the acceptor compartment are assumed to be zero at the start of the experiment. At different time points, the cumulative drug amount per unit area in the receptor q(t) is determined and plotted versus time t (Figure 20.1). After some time, the flux... 

Figure 20.1 Plotting cumulative amount versus time in a Franz-diffusion cell experiment results in a curve approaching a straight line.

The second aspect refers to the protein nature of enzymes. In 1894 Fischer (Fischer, 1909) stated that amongst the agents which serve the living cell the proteins are the most important. He was convinced that enzymes are proteins. The role of this key problem may be illustrated with a citation from Fruton (1979) ... the peptide theory was indeed only a hypothesis fifty years after Franz Hofmeister and Emil Fischer advanced it... (in 1902). The nature and stracture of proteins remained unknown throughout the 19th century remarkably, technological applications were nevertheless put into practice since the middle of the century (see above), based on their action, eventually recognized as catalysis, only. 

Franz diffusion cells apparatus (Crown Glass Company Inc., NJ), constant temperature water bath (Yamato Scientific Co. Ltd., Japan) and spectrophotometer (Shimadzu Siesakusho Ltd, Japan)... 

The in vitro diffusion studies for each sample were carried out by using the Franz diffusion cells with a diffusional area of about 1.76cm2. The acceptor compartment of the apparatus was filled with the buffer solution pH 6, USP [21], and maintained at 37 0.5°C via a circulating water system. The diffusion membrane (the cellulose membrane with a molecular weight cut-off point of 1000 or the hairless mouse skin) previously prepared was placed between die donor and the acceptor compartments of the assembly. An accurately weighed 4g of sample was then placed in the donor cell and the diffusion process was started. The solution in the acceptor compartment was continuously stirred with a small magnetic stirrer to maintain the sink conditions. Aliquots from the receptor cells were removed at 0.5,2,4, 8 and 24 h time intervals and replaced with equal... 

Hirche HJ, Franz C, Bos L, Bissig R, Lang R, Schramm M Myocardial extracellular K+ and H + increase and noradrenaline release as possible cause of early arrhythmias following acute coronary occlusion in pigs. J Mol Cell Cardiol 1980 12 579-593. 

Franz diffusion cells (FDC) remain the workhorse of all permeation experiments in transdermal studies. FDCs use the permeation of a solute, assessed by high pressure liquid chromatography (HPLC) or radiation, to evaluate the effect of penetration... 

Figure 5 Plot of conductivity enhancement ratios (ERs) in INSIGHT at 24 hours versus permeability ERs in FDC for 12 enhancer formulations. A strong linear correlation indicates the validity of observations in INSIGHT when compared with those from traditional tools such as FDC. Abbreviations. INSIGHT, in vitro skin impedance guided high-throughput screening FDC, Franz diffusion cell.

VALIDATION OF IN VITRO SKIN IMPEDANCE GUIDED HIGH-THROUGHPUT SCREENING WITH FRANZ DIFFUSION CELLS... 

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