"sometimes the FDA approves a drug for general use but requires the manufacturer to continue to monitor its effects; during this phase the drug may be tried on slightly different patient populations than those studied in earlier trials"@en-us . . "phase IV"@en-us . "phase IV clinical trial"@en-us . "phase IV clinical trial"^^ . "00793529-n"^^ . "0"^^ . "100793529"^^ . . . . . . . . "100744320"@en-us . "0"^^ . . .