Current:
"code" : {
"coding" : [

{ "system" : "http://snomed.info/sct", "code" : "387406002", "display" : "Sulfonamide (substance)" }

],
"text" : "sulfonamide antibacterial"
},

Change to:
"code" : {
"coding" : [

{ "system" : "http://snomed.info/sct", "code" : "763875007", "display" : "Product containing sulfonamide (product)" }

],
"text" : "Sulfonamide-containing product"
},

Reason:
Medicinal product class concepts are to be represented using concepts drawn from the SNOMED CT Product hierarchy, not the substance hierarchy. That way implementers can use the NLM RxClass tool to identify the specific RxNorm drugs that fall within the class. This is not possible with SCT substances. The current value set is found here https://vsac.nlm.nih.gov/valueset/2.16.840.1.113762.1.4.1114.14/expansion/Latest