Significant cutaneous damage may result from pentazocine injections as seen in four patients with the possible consequences of parenterally administered pentazocine. Clinical findings in these cases and in animal studies subsequently done suggest that the inflammation, sclerosis and fibrosis, and ulceration result from local effects mediated by the pentazocine.
Parks DL, Perry HO, Muller SA. Cutaneous Complications of Pentazocine Injections. Arch Dermatol. 1971;104(3):231–235. doi:10.1001/archderm.1971.04000210005002