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→Physiological Variables
Thus the extent of ionisation of a drug and so it's extent of absorbtion, depneds upon its '''pK<sub>a</sub>''' and the pH within the body compartment.
Thus the extent of ionisation of a drug and so it's extent of absorbtion, depneds upon its '''pK<sub>a</sub>''' and the pH within the body compartment.
Due to the above drugs can become '''ion trapped''' in certain body compartments. If it is assumed that the ionised fraction is unable to cross cell membranes and the unionised fraction is; then a weak acid will become greatly concentrated in an environment with a high pH. This is because it will donate it's spare protons to the basic elements in the high pH environment and then will be unable to cross out of the environment as the drug is now ionised; it has been '''trapped'''.
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