pregabalin + PF-00489791

Combination of **pregabalin** (a well-established alpha-2-delta ligand approved for neuropathic pain) and **PF-00489791** (an experimental phosphodiesterase 5A (PDE5A) inhibitor initially developed by Pfizer). This combination was investigated in clinical trials for improved analgesic efficacy in post-herpetic neuralgia, a chronic neuropathic pain condition. Pregabalin reduces neuronal excitability by inhibiting voltage-gated calcium channels, while PF-00489791 acts via a distinct mechanism by inhibiting PDE5A, likely modulating cyclic GMP signaling and influencing pain pathways[8][9]. The combination was expected to provide enhanced pain control compared to pregabalin monotherapy[4][5][6].