Intranasal Semax achieves approximately 60-70% bioavailability with superior CNS penetration through direct nose-to-brain pathways, while subcutaneous administration offers 80-90% systemic bioavailability but slower brain delivery. Intranasal is preferred for cognitive applications due to rapid CNS access.
Comparative pharmacokinetic studies demonstrate intranasal administration's advantages for brain-targeted delivery despite lower systemic bioavailability.