Drugs can affect the renal excretion of other drugs leading to pharmacokinetic drug interactions. The mechanisms for drug-induced alterations in renal drug clearance are not fully known. One mechanism involves the alteration of urinary pH. Another mechanism depends on the tubular transport mechanisms. If two drugs are eliminated through the same tubular secretion protein, then one or both drugs may have reduced excretion, increased serum levels, and thus a greater chance for causing side effects.
A few examples of such interactions are outlined in Table 2. There is also the possibility that a drug may induce or inhibit the expression or function of a particular transport protein. A drug that can cause an altered action or elimination of another drug is often called the ‘precipitant drug’ in a drug-drug interaction. Table 3 lists some examples of common precipitant drugs implicated in drug interactions due to altered active tubular secretion. ventolin inhaler
TABLE 2 Specific examples of renal tubular pharmacokinetic interactions
|Amphotericin B Cephalosporins Cimetidine MethotrexateNonsteroidal anti-inflammatory drugsPenicillinsProbenecidSalicylatesSulfinpyrazone|