Gastro-intestinal tract, absorption

Penicillamine is well absorbed (40-70%) from the gastro-intestinal tract and, therefore, has a decided advantage over many chelating agents. Food, antacids, and iron reduce its absorption, so it should be taken on an empty stomach. Preferably, the... 

Kobayashi M, Sada N, Sugawara M, Iseki K, Miyazaki K (2001) Development of a new system for prediction of drug absorption that takes into account drug dissolution and pH change in the gastro-intestinal tract. Int J Pharm 221 87-94. 

Hunjan, M.K. and D.F. Evered. 1985. Absorption of glutathione from the gastro-intestinal tract. Biochim Biophys Acta 815 184. 

Guarini, S., and W. Ferrari. 1985. Olive oil-provoked bile-dependent absorption of heparin from gastro-intestinal tract in rats. Pharmacol Res Commun 17 685. 

Most studies show that bioaccumulation predominantly results from chemical absorption directly from water via the respiratory surface (e.g., gills and/or skin) of the organism (i.e., bioconcentration) and from diet via the gastro-intestinal tract (i.e., biomagnification). Exceptions occur e.g., phytoplankton species generally do not absorb chemical by dietary ingestion, organisms obtain chemical via maternal transfer, and some species contain unique mechanisms for chemical uptake and elimination. 

In addition to the potential of liberating the active drug upon absorption, orally applicable prodrugs require a sufficient stability in the gastro-intestinal tract which is most importantly pH-dependant chemical stability. This can be studied with simulated gastrointestinal fluids (Balbach and Korn 2004). Also... 

Manganese in the human is also thought to be absorbed maximally in the duodenum in the II valence state. Therefore, as with manganese uptake by plants, the pH of the upper gastro-intestinal tract might be expected to be of importance in the absorption of manganese by the human. 

To produce an effect, a drug must first enter the blood stream and be carried to the target organ. With the exception of intravenous injection, the first process is that of absorption, either from the gastro-intestinal tract, from an injection site, or from the lungs. 

Fig. 2. Factors which influence the passage and absorption of drugs in the gastro-intestinal tract.

The advantages of bulk powders are that the dry powders may be more stable than their liquid-based equivalent, and absorption from the gastro-intestinal tract will be quicker than with tablets or capsules. 

The very low water solubility of key cannabis constituents aggravates still further the well-known variability of absorption from the gastro-intestinal tract, resulting in poor predictability of both the timing and intensity of peak effects by the oral route. Titration of dose against symptom relief, as is the norm for most individuals who smoke cannabis medicinally, is very difficult in these circumstances. An additional drawback is the production of larger quantities of the reputedly psychoactive metabolite 11-OH-THC as a result of the hepatic first-pass phenomenon. The use of whole plant cannabis-based medicinal extracts in liquid form delivered by a pump action oromucosal spray (Whittle et al. 2001) represents an attempt to overcome these problems and permit the patient to self-titrate to an optimal individualised daily dose. 

Cohn BNE. 1932. Absorption of compound solution of iodine from the gastro-intestinal tract. Arch Intern Med 49 950-956. 

The recommended dose is 10,000 to 20,000 units given intramuscularly every 6 hours and accompanied by careful studies of the renal function i " . In this way bacitracin is absorbed readily from the site of injection although pain and some injury may be observed there. It has been used in the treatment of staphylococcal bacteremias, osteomyelitis, bacterial endocarditis, and in the control of urinary tract infections either alone or in combination with other drugs . Local injection into circumscribed areas, such as furuncles and abscesses, has also been successful. Orally, bacitracin has been used either alone or in combination with other antibiotics as an intestinal antiseptic i, for example in the pre-operative sterilization of the bowel. Because of the poor absorption from the gastro-intestinal tract, no special precautions are necessary. 

Orally, both antibiotics are used for the treatment of intestinal infections due to susceptible organisms and, in combination with other drugs, for bowel sterilization prior to surgery. Owing to poor absorption from the gastro-intestinal tract, this form of application has rarely led to side-effects. Both are used either alone or in combination with other antibiotics in a variety of ointments and solutions for topical application on infected surface lesions of skin and mucuous membranes " . Allergic reactions have rarely been observed. 

USE Contact herbicide used also to produce desiccation and defoliation. Toxicity Minimal absorption from gastro -intestinal tract although distension and irritation occur after large doses in exptl animals Dalgaard-Mikkelsen, Poulsen, Pharmacol. Rev. 14, 225 (1962). 

Amodiaquine hydrochloride is readily absorbed from gastro-intestinal tract after oral administration, and higher concentrations occur in erythrocytes, kidney, liver, lungs and spleen than in the plasma. After absorption it is slowly released into the blood and excreted in the urine for at least seven days after a single dose. The rate of excretion is increased in acid urine (5,7). Amodiaquine is altered rapidly in vivo to yield products which appear to be excreted slowly, and thus have a prolonged suppressive activity (44). 

Clonidine hydrochloride is readily absorbed by oral route with an absorption time of 2 to 4 hours (9). Drug is well absorbed from the gastro-intestinal tract. It may also be absorbed when applied topically to the eye, clonidine is well absorbed percutaneously following topical application of a transdermal system to the arm or chest. Plasma clonidine concentrations of 2 ng/mL have been detected one hour after administration of a single 0.39 mg oral dose of radiolabeled drug. Peak plasma concentrations following oral administration occur in approximately 3-5 hours (1). 

Absorption route Can enter the body by inhalation or ingestion. Immediate eftects Irritates the eyes, skin and gastro-intestinal tract. Corrosive to the respiratory organs. Inhalation can cause lung edema. In serious cases risk of death. Effects of prolonged/repeated Mposure Can affect the blood. Can cause kidney damage. Can impair sense of smell. ... 

CDs modify the bioavailability of drugs only. Recognizing that orally administered CD-complexes dissociate in the gastro-intestinal tract before absorption, and it is the drug only that is absorbed, it is hoped that after favourable experiences with the first fully documented drugs, only the pharmakokinetic and clinical trials will be required by the Health Authorities without the complete pre-clinical studies. 

ETi, is removed by extrinsic processes, such as nose blowing. For the other regions, clearance of inhaled material is competitive between particle transport processes (such as macrophage uptake and ciliary action) to the gastro-intestinal tract and to lymph nodes and absorption into blood. 

---