>1 Plasma nicotine levels produced by chewing nicotine gum were compared with those obtained by cigarette smoking under conditions of controlled urinary pH.>2 Although absorption was slower, plasma levels comparable to cigarette smoking were built up on 4 mg (but not 2 mg) nicotine gum.>3 Urinary excretion of nicotine was influenced markedly by pH and the rate of urine flow.>4 Plasma nicotine was higher under alkaline compared to acidic conditions (P < 0.001) but the rate of urinary nicotine excretion appeared to have little effect on the plasma level.
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