Just for referance:-
Oral Absorption
The oral mucosa has a thin epithelium and a rich vascularity that favors absorption, but contact is usually too brief, even for drugs in solution, for appreciable absorption to occur. A drug placed between the gums and cheek (buccal administration) or under the tongue (sublingual administration) is retained longer so that absorption is more complete.
A good article on Oral absorption is at;
http://www.positivehealth.com/permit...alth/lea13.htm
Exothermic & Endothermic reactions
An exothermic reaction releases energy. The energy change that accompanies a reaction can be written in the equation.
CH4(g) + 2O2 (g) -> CO2(g) + 2H2O(I) + 213 Kcal
Here the 213 kcal are a product and appear on the right hand side of the equation. the reaction produces energy so the sign for the 213 kcal is negative, (-213 kcal). The reaction is exothermic.
The amount of energy change is proportional to the mass of material consumed in the reaction. If two moles of methane are burned the heat effect will be doubled.
An endothermic reaction uses energy as a reactant.
N2(g) + O2(g) + 43 Kcal --> 2 NO(g)
The energy change that accompanies a reaction can be written in the chemical equation. Here the 43 kcal are needed to make the reaction occur. The sign for the energy change is +. This is an endothermic reaction. The surroundings must provide energy to make this reaction happen. We are fortunate that the oxygen and nitrogen require energy to force them to react. Otherwise we could have lost our atmosphere in a burst of flame years ago.