The following pages will illustrate how altering the pH of urine can be used to enhance the efficiency of elimination of a drug. This approach can be put to good use e.g. in case of barbiturate overdose (an acidic drug).

Urinary pH can be manipulated rather easily to become more alkaline (using bicarbonate), or more acidic (using NH₄CL).

Clearly, in the kidney a drug can move between the plasma and the urinary space in the tubule through two roads.

1. At the level of the glomerulus, from the plasma to the urinary space.
2. At the level of the tubule, in the reverse direction, from the urinary space back into the plasma.

The type of barrier the drug has to cross in both instances is different.

 

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