ABSTRACT
This chapter presents classification & mode of action, indications & dermatological uses, formulations/presentation, dosages & suggested regimens, baseline investigations, considerations & monitoring, contraindications, cautions, important drug interactions, adverse effects & their management, use in special situations, and essential patient information of Sulfapyridine (SP) & Sulfamethoxy-pyridazine (SMP). The produce licence for SP and SMP has lapsed and they are only available on a named patient basis. SP and SMP are used as second-line agents when treatment with dapsone has failed or is contraindicated. SP and SMP bind to plasma proteins and may displace other protein bound drugs, resulting in increased free levels of the displaced drug with potential toxicity. SP has been shown to cause oligospermia and infertility in males. The sulfonamide antibacterial drugs, SP and SMP are structurally related to para-aminobenzoic acid (PABA). Their antibacterial effects are related to competitive inhibition of the bacterial enzyme dihydropteroate synthase, which plays a key role in converting PABA to dihydrofolic acid.
