Aspirin absorption

Pharmacokinetics BSS undergoes chemical dissociation in the Gl tract. Two BSS tablets yield 204 mg salicylate. Following ingestion, salicylate is absorbed, with greater than 90% recovered in the urine plasma levels are similar to levels achieved after a comparable dose of aspirin. Absorption of bismuth is negligible. 

Theabsorptionof orally administered drug is altered e.g. achlorhydria reduces aspirin absorption. 

The relationship between gastric residence time (GRT) and the variability in aspirin absorption from enteric-coated tablets has also been evaluated with the Heidelberg capsule [59], The study design was a single dose crossover study with men and women, fasted and fed. In addition to pH monitoring, plasma concentrations of salicylic acid and salicyluric acid in plasma and urine were measured. GRT was significantly delayed in the fed state, and women had longer GRT compared with men. 

Aspirin absorption may be delayed when overdose quantities are consumed, especially of enteric-coated or slow-release preparations. This must be considered when interpreting serum salicylate values, especially for specimens obtained earlier than 6 hours after ingestion. Repeat testing within 2 to 3 hours is recommended to ensure that absorption is complete subsequent testing provides an indication of effectiveness of therapeutic intervention. Because of the aforementioned complications, proper assessment of salicylate intoxication requires sound clinical evaluation in combination with serum salicylate levels. 

It is clear from Figure 9.16 that aspirin absorption is more rapid from solution than from tablet formulations. This rapid absorption of aspirin is an indication that the rate of absorption is dissolution rate limited. A general relationship describing the dissolution of a drug was first reported by Noyes and Whitney (38). The equation derived by those authors is as follows ... 

In 12 healthy subjects the extent of absorption of a single 650-mg dose of aspirin was unaffected by colestipol 10 g. However, the rate of aspirin absorption was increased by colestipol at 60 minutes after the dose the plasma level was increased by about 40%. No particular precautions seem to be necessary during concurrent use. 

Wood JH. Effect of food on aspirin absorption. Lancet 961) ii, 212. 

Sodium sulfate and castor oil used as laxatives can cause a modest, but probably clinically unimportant, reduction in aspirin absorption. 

Khoury W, Geraci K, Askari A, Johnson M. The effect of cimetidine on aspirin absorption. 

Mason WD, Winer N. Influence of food on aspirin absorption from tablets and buffered solutions. J Pharm Sci 1983 72(7) 819-821. 

Many pharmaceutical compounds contain chromophores that make them suitable for analysis by UV/Vis absorption. Products that have been analyzed in this fashion include antibiotics, hormones, vitamins, and analgesics. One example of the use of UV absorption is in determining the purity of aspirin tablets, for which the active ingredient is acetylsalicylic acid. Salicylic acid, which is produced by the hydrolysis of acetylsalicylic acid, is an undesirable impurity in aspirin tablets, and should not be present at more than 0.01% w/w. Samples can be screened for unacceptable levels of salicylic acid by monitoring the absorbance at a wavelength of... 

Molar absorptivity. 502 Molecular ion (M+), 410 Molecular mechanics. 130 Molecular model, dopamine, 930 acetaminophen, 29 acetylene, 18 adenine, 67 adrenaline, 323 alanine, 28, 1016 alanylserine, 1028 rr helix, 1039 p-aminobenzoic acid, 25 anti periplanar geometry, 387 a recoline, 79 aspartame, 29 aspirin. 17 ball-and-stick, 61 /3-pleated sheet, 1039 p-bromoacetophenone, 449 bromocyclohexane, 121 butane, 80... 

Food containing salicylate (curry powder, paprika, licorice, prunes, raisins, and tea) may increase the risk of adverse reactions. Coadministration of the salicylates with activated charcoal decreases the absorption of the salicylates. Antacids may decrease the effects of the salicylates. Coadministration with the carbonic anhydrase inhibitors increases the risk of salicylism. Aspirin may increase the risk of bleeding during... 

Do not combine with an antiplatelet agent o If patient experiences a systemic embolism while receiving warfarin and has a therapeutic INR, add aspirin 75-100 mg/d. For patients unable to take aspirin, then add dipyridamole 400 mg/d or clopidogel 75 mg/d. Immediate release dipyridamole needs an acidic gastric pH (<4) for adequate absorption... 

M Rowland, S Riegelman, PA Harris, SD Sholkoff. Absorption kinetics of aspirin in man following oral administration of an aqueous solution. J Pharm Sci 61 379-385, 1972. 

G. Levy, J. R. Leonards, and J. A. Procknal, Development of in vitro dissolution tests which correlate quantitatively with dissolution rate-limited drug absorption in man, J. Pharm. Sci., 54, 1719-1722 (1966). K. A. Javaid and D. E. Cadwallader, Dissolution of aspirin from tablets containing various buffering agents, J. Pharm. Sci., 61, 1370-1373 (1972). 

M. Nowak, B. Brundhofer, and M. Gibaldi, Rectal absorption from aspirin suppositories in children and adults, Pediatrics, 54, 23 (1974). 

From the uv absorption spectra, a suitable wavelength is found for the simultaneous detection of aspirin, phenacetin and caffeine. Using phenacetin as internal standard, response factors are calculated for aspirin and caffeine and the results are used for the quantitative determination of aspirin and caffeine in an analgesic tablet. 

The answer is c. (Hardman, pp 887, 889.) Bile acid-binding resins bind more than just bile acids, and binding of simvastatin to cholestyramine is the most likely mechanism for decreased Gl absorption. Cholestyramine may also bind to several other drugs, including digoxin, benzothiadiazides (thiazides), warfarin, vancomycin, thyroxine (T4), and aspirin. Medications should be given one hour before or four hours after cholestyramine. 

Absorption Spectrum The polarized absorption spectrum of a single crystal of aspirin was measured which indicated that aspirin may be spectroscopically treated as perturbed benzoic acid.59... 

The absorption coerricient of a collimated beam of G Co z-radiation was determined for aspirin. See reference 76 for details. 

The infrared spectrum has been used to determine aspirin in combination products. Accuracy of 1-2% has been claimed (cf. 90,91). For aspirin, the absorption maximum at 1765 cm l has been used.92... 

Liberman, S.V., Kraus, S.R., Murray, J., and Wood, J.H., Aspirin formulation and absorption rate I. Criteria for serum measurements with human panels, J. Pharm. Sci., 53,1486,1964. 

For a drug to interact with a target, it has to be present in sufficient concentration in the fluid medium surrounding the cells with receptors. Pharmacokinetics (PK) is the study of the kinetics of absorption, distribution, metabolism, and excretion (ADME) of drugs. It analyzes the way the human body deals with a drug after it has been administered, and the transportation of the drug to the specihc site for drug-receptor interaction. For example, a person has a headache and takes an aspirin to abate the pain. How does the aspirin travel from our mouth to reach the site in the brain where the headache is and act to reduce the pain ... 

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