Drug absorption interactions affecting

Another important type of physical chemical interaction that may alter absorption is that of drug binding or adsorption onto the surface of another material. As with complexation and micellarization, adsorption will reduce the effective concentration gradient between gut fluids and the bloodstream, which is the driving force for passive absorption. While adsorption frequently reduces the rate of absorption, the interaction is often readily reversible and will not affect the extent of absorption. A major exception is adsorption onto charcoal, which in many cases appears to be irreversible, at least during the time of residence within the GIT. As a result, charcoal often reduces the extent of drug absorption. Indeed, this fact... 

Drug/Food interactions Food enhances the bioavailability of metoprolol and propranolol this effect is not noted with nadolol, bisoprolol, or pindolol. The rate of carteolol and penbutolol absorption is slowed by the presence of food however, extent of absorption is not appreciably affected. Sotalol absorption is reduced approximately 20% by a standard meal. 

Drug/Food interactions Administration of tolmetin with milk decreased total tolmetin bioavailability by 16%. When tolmetin was taken immediately after a meal, peak plasma concentrations were reduced by 50%, while total bioavailability was again decreased by 16%. Peak concentration of etodolac is reduced by about 50% and the time to peak is increased by 1.4 to 3.8 hours following administration with food however, the extent of absorption is not affected. Food may reduce the rate of absorption of oxaprozin, but the extent is unchanged. 

Drug/Food Interactions Food does not affect the extent of absorption of levetiracetam, but it decreases C ax by 20% and delays T ax by 1 -5 hours. 

Drug/Food interactions Absorption of most penicillins is affected by food these medications are best taken on an empty stomach, 1 hour before or 2 hours after meals. Penicillin V may be given with meals however, blood levels may be slightly higher when taken on an empty stomach. Amoxicillin and amoxicillin/potassium clavulanate tablets may be given without regard to meals. 

Drug/Food interactions Food impairs the absorption of lincomycin do not take anything by mouth (except water) for 1 to 2 hours before and after lincomycin. Clindamycin absorption is not affected by food. 

Factors affecting the delivery include the physical form of the drug, the entry into the body, the design and the formula of the product. This may depend on the physicochemical properties of the excipients, the control of the drug-excipient interaction at the absorption site. Thus, polysaccharides may play an essential role for effectiveness and reliability of the different drug delivery systems. 

Jackson, K., Young, D., and Pant, S. (2000), Drug-excipient interactions and their affect on absorption, PSTT, 3(10), 336-345. 

Welling PG. Interactions affecting drug absorption. Clin Pharmacokinet 1984 9 404-34... 

Factors affecting drug absorption include formulation, disease state, food effect, and drug-drug interaction. Formulations used for oral administration include solutions, suspensions, capsules, and uncoated and coated tablets. Depending on the formulation of a drug, the absorption characteristics may differ substantially. 

This chapter provides basic information on the physicochemical mechanisms of drug absorption and how the processes of absorption are affected by the physicochemical properties of the drug and its formulation, by the interaction of the drug with the aqueous phase and by the nature of the membrane. Oral absorption is discussed in some detail and the influence of the following in determining bioavailability should become clear ... 

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