Drug solubility membrane surface

These mixing motions will tend to improve drug absorption for two reasons. Any factor that increases rate of dissolution will increase the rate (and possibly the extent) of absorption, especially for poorly water-soluble drugs (BCS Classes II and IV). Since rate of dissolution depends on agitation intensity, mixing movements will tend to increase dissolution rate and thereby influence absorption. As rate of absorption depends directly on membrane surface area, and since mixing increases the contact area between drug and... 

Factors that influence drug dialyzability in chronic ambulatory peritoneal dialysis include drug-specific characteristics (e.g., molecular weight, solubility, degree of ionization, protein binding, and VD) and intrinsic properties of the peritoneal membrane (e.g., blood flow, pore size, and peritoneal membrane surface area). 

The amino group in chitosan has a pKa value of about 6.5. Therefore, chitosan is positively charged and soluble in acidic to neutral solutions with a charge density dependent on pH and the deacetylation extent. In other words, chitosan readily binds to negatively charged surfaces such as mucosal membranes. Chitosan enhances the transport of polar drugs across epithelial surfaces, and is biocompatible... 

A drug diffusion experiment has been carried out over a long period of time to reach a steady-state condition. The data shown in Figure 6.10 have been collected. Calculate the partition coefficient and the drug solubility. The drug diffusion coefficient of 2 x Kb6 cm2/sec was independently determined by a time-lag experiment. The surface area, volume, and thickness of the membrane reservoir are 1.2 cm2, 32.4 cm3, and 50 pm, respectively. The total amount of drug in the membrane reservoir is 25 mg. 

In experiments, dilution or volume shifts from osmotic gradients between plasma and buffer compartments may be considerable and require correction. Poorly water-soluble drugs are difficult to study because use of organic solvents interferes with equilibrium distribution, and such drugs may also aggregate and adhere to membrane surfaces. ... 

The small intestine is the most important organ for drug absorption in the gastrointestinal tract. The surface area of the intestine is approximately 200 m (Caspary, 1992) because of the presence of well-developed vilh. Collapsibility, drug solubility, and membrane permeability are the most influential factors in determining Fa- Solubility in aqueous solution is a critical factor in optimizing Fa (Ku, 2008). 

Drugs taken orally are slow to act. Most are absorbed in the small intestine where the villi, which penetrate into the lumen, present a large surface area. Unfortunately in order to pass through the gut wall into the bloodstream the drug has to become dissolved in its cell s membranes and to achieve this it needs to be lipid-soluble. 

Flux depends on the product of membrane permeability of the solute times the concentration of the solute (summed over all charge state forms) at the water side of the donor surface of the membrane. This concentration ideally may be equal to the dose of the drug, unless the dose exceeds the solubility limit at the pH considered, in... 

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