Gastro-intestinal system

Abdominal pain Gastro-intestinal system disorders 46,305 1.3... 

Another important physicochemical parameter is the pKa, which describes the ionisation state of a compound at a given pH. The ionisation state of a compound in the different components of the gastro intestinal system (stomach, jejunum, ileum and colon) is crucial for the understanding of drug absorption (Dressman). Ionised compounds generally have better solubility, but passive permeation through the membrane is limited (Comer). 

Dressman reviewed the methodologies used for simulating bio fluids. These methodologies focus on the solubility behavior and dissolution rate in solvents, which mimic the fluids in the gastro intestinal system like Fessif and Fassif. These dissolution tests were invented for better prediction the in vivo performance of drug products. They are barely comparable with solubilities in buffered aqueous media and have a limited throughput of a couple of compounds a day. 

NOTE For these categories the specific target organ/system that has been primarily affected by the classified substance may be identified, or the substance may be identified as a general systemic toxicant. Attempts should be made to determine the primary target organ of toxicity and classify for that purpose, e.g. hepatoxicants, neurotoxicants. One should carefully evaluate the data and, where possible, not include secondary effects, e.g. a hepatotoxicant can produce secondary effects in the nervous or gastro-intestinal systems. ... 

For example, chapter 1 of the British National Formulary contains drugs used to treat conditions relating to the gastro-intestinal system. 

General. The purpose of the medical procedures outlined in the standard is to establish a baseline for future health monitoring. Persons unusually susceptible to the effects of anoxia or those with anemia would be expected to be at increased risk. In addition to emphasis on the CNS, respiratory and gastro-intestinal systems, the cardiovascular system, liver, and kidney function should also be stressed. 

Beneficial Effects on Gastro-Intestinal System and Micronutrient Bioavailability... 

Pyridine may cause central nervous system depression, irritation of skin and respiratory tract Large doses may produce gastro-intestinal disturbances, kidney and liver damage (Refs 3 4)... 

Quong, D., O Neill, I. K., Poncelet, D., and Neufeld, R. J., Immobilized Cells Basics and Applications, in Gastro-Intestinal Protection of Cellular Component DNA within an Artificial Cell System for Environmental Carcinogen Biomonitoring (R. G. Wijffels, R. M. Buitelaar, H. S. Wessels, C. Bucke, and J. Tramper Eds.), p. 814. Elsevier Science, Amsterdam (1996). 

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. 

The side-effects of cardiac glycosides are mostly caused by electrophysiological/neuronal phenomena. Gastro-intestinal adverse reactions are probably triggered by effects on the central nervous system. Various types of cardiac arrhythmias are caused by the influence of the drugs on nodal tissues in the heart. The risk of arrhythmia is strongly enhanced by low plasma potassium concentrations. 

Venkatesan, N., et al. 2006. Gastro-intestinal patch system for the delivery of erythropoietin. J Control Release 111 19. 

Puchel G, Montisci M-J, Dembri A, Durrer C, Duchene D (1997) Mucoadhesion of colloidal particulate system in the gastro-intestinal tract,. Europ J Pharm Biopharmaceut 44 25-31... 

Toxicity. Aconitine affects both the heart and the central nervous system and is one of the most potent and quick-acting poisons. It is well absorbed from the gastro-intestinal tract and death may occur within a few minutes. The estimated minimum lethal dose is 2 mg of aconitine, 5 ml of aconite tincture (25% v/v) or 1 g of aconite root, although recovery after ingestion of 10 mg of aconitine has been reported. 

Disposition in the Body. Cocaine is normally only used as a surface anaesthetic in the eye, ear, nose, and throat because of the possibility of systemic toxic effects when given by other routes. Addicts may inject it or use it as a snuff it is less toxic when taken orally due to hydrolysis in the gastro-intestinal tract. 

Toxicity. Coniine is well absorbed from the gastro-intestinal tract and is very poisonous the estimated minimum lethal dose is 150 mg and toxic symptoms may occur after ingestion of 60 mg. Death may occur within 30 minutes or be delayed 3 to 12 hours. Coniine resembles nicotine in its peripheral action but produces more pronounced paralysis of the central nervous system and of the skeletal muscle nerve-endings. 

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