1. By Stomach: Gastro-intestinal Route. - This is the most common and convenient method. After medicines are swallowed they enter circulation through the walls of the bloodvessels (which permeate the mucous membrane of the stomach and intestines), portal veins, and lacteals, so that when the intestinal contents reach the ileo-caecal valve they consist of excrementitious matter and food refuse. If the stomach be healthy and empty, crystalloids in solution quickly pass through the vessel-walls, but colloids (albumin, fats, gelatin, gums, etc.) have to be digested and emulsified before they can be absorbed; the albuminous drugs (proteids) are transformed in the stomach by pepsin and gastric juice into soluble peptones, and there as such these, along with soluble crystalline salts, diffuse readily into the blood, often giving positive effect within an hour; the sugar, starchy, fatty, gummy, gelatinous, resinous, gumresinous and oleoresinous drugs, without suffering much change from the stomach secretions, pass into the duodenum, where the bile, intestinal and pancreatic juices, within 3-4 hours, convert the starches into sugar (which in part may go finally into lactic acid and fat), emulsionize and saponify the fats, oils, etc., separating them into glycerin and fat acids, the latter meeting alkaline bases, forming diffusible soaps; the resins, alone and in combination, within 4-10 hours, become broken up by these same alkaline juices (associated alkaline salts often facilitating), and either are converted into a soluble form for systemic ingestion, or simply are eliminated from the liver [whose secretion (bile) they have stimulated], thereby being allowed to pass into the lower intestine to stimulate intestinal gland secretion, or to act somewhere along the tract as a local irritant or stimulant, thereby aiding peristalsis. All drugs taken from the intestinal canal have to pass through the liver before reaching general circulation, and in this passage they may become medicinally very much changed, modified, or even destroyed; again, some drugs may be excreted into the intestine along with the bile, and never reach further circulation, hence these disadvantages, along with that of required palatable form, preclude sometimes the adoption of this avenue.
2. By Skin:
Hypodermic (Hypodermatic). This consists in injecting medicinal solutions (v-l 5; .3 1 Ml. (Cc.)) into subcutaneous areolar tissue with a syringe (needle) - a method always more or 1ess painful. Quick absorption here takes place by the lymphatics and capillary vessels, giving the advantage of full action of the quantity of drug used, without any possible changes from the intestinal secretions or processes; must here employ only clear, neutral (never acid), aqueous solutions of drugs, as otherwise intractable sores, sloughing, etc., might result around the punctures; must also avoid veins, injecting only on the external parts of the legs, thighs, arms, also abdomen, back, and buttocks (4 Cm.; 1 3/5' behind the great trochanter). In the process of hypodermoclysis a sterilized trocar is employed, and several pints of saline solution (7/10 1 p. c.) injected, to antagonize, or to wash out and dilute any septic poison (uraemia, septicaemia) cholera-collapse, diabetic coma, shock, etc.; here insert trocar in subcutaneous tissue of abdomen or thigh, and control rate of flow alone by elevating or lowering the vessel containing the required amount of liquid; dissipate any tumefaction by careful massage; admit no air or foreign matters.