Fig. 1

Schematic illustration of triptan pharmacology from a neuropharmacokinetic point of view. Unbound target-site concentrations are governed by interrelated and interconnected processes including the passage of unbound drug across the blood-to-tissue endothelial interfaces and cellular barriers. Triptans are known to exert their action through 5-HT_1B/1D/1F receptors. Their proposed mode of action involves vascular, trigeminovascular, and central mechanisms. For triptans to cause these actions, they need to cross endothelial barriers including the non-nervous system (NS) barriers, PNS barriers (BNB; blood-nerve barrier), and CNS barriers (BBB; blood-brain barrier or BSCB; blood-spinal cord barrier). K_{p, uu} is the unbound tissue-to-plasma concentration ratio describing the extent of unbound drug transport across an endothelial barrier and K_{p, uu, cell} is the unbound intracellular-to-extracellular (interstitial) concentration ratio describing the extent of cellular barrier transport. NB: for simplicity, only key pharmacodynamic mechanisms are illustrated