How does urine pH affect the plasma half-life of pseudoephedrine, an ingredient in Multi-Action ACTIFED Dry Coughs?

For pseudoephedrine, an ingredient in Multi-Action ACTIFED Dry Coughs, urine acidification markedly decreases plasma half-life and alkalinisation increases it; approximately 5.5 hours was reported at urine pH 5.0–7.0, but human pharmacokinetic information for the combination is unavailable.