Key result
Urinary acidification (pH 5.0) resulted in a plasma elimination half-life of mexiletine of 2.8 hours, compared to 8.6 hours when urine was alkaline (pH 8.0).
Why the study?
Does urinary pH influence the plasma elimination half-life of mexiletine?
Does urinary pH influence the plasma elimination half-life of mexiletine?
Absolute Event Rate: 2.8% vs 8.6%
The elimination half-life of mexiletine is highly dependent on urinary pH, indicating a need for pH monitoring to ensure therapeutic precision.
May support pH monitoring for mexiletine dosing; leaves open whether this improves outcomes in practice.
1 The plasma elimination half-life of mexiletine was measured in four subjects when the urine was rendered (a) acidic and (b) alkaline. 2 Urinary acidification (pH 5.0) was associated with a plasma elimination half-life of 2.8 h and 57.5% of the intravenous dose was excreted in the urine within 48 hours. When the urine was alkaline (pH 8.0) the half-life increased to 8.6 h with negligible amounts of drug appearing in the urine. 3 Urinary pH varies widely in cardiac patients and should be controlled or monitored to provide better therapeutic precision with mexiletine.
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KIDDIE et al. (1974) studied this question. Urinary acidification (pH 5.0) vs. Alkaline urine (pH 8.0) was evaluated on Plasma elimination half-life of mexiletine. Urinary acidification (pH 5.0) resulted in a plasma elimination half-life of mexiletine of 2.8 hours, compared to 8.6 hours when urine was alkaline (pH 8.0).
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