Melanocortin receptor-specific linear peptides of the formula where R1, R2, R3, R4, R5, R6, R7, R8, R9 and R10 are as defined in the specification, compositions and formulations including peptides of the foregoing formula or salts thereof, and pharmaceutical compositions for preventing, ameliorating or treating melanocortin-1 receptor-mediated or responsive diseases, indications, conditions and syndromes.