Modifiers matching peptide:

• antigenic,
• active,
• natural,
• psychoactive,
• endogenous,
• synthetic,
• addictive,
• interesting,
• minor,
• proinflammatory,
• analgesic,
• anticancer,
• foreign,

Simple categories matching analgesic:

• agent,
• chemical,
• compound,
• drug,
• medication,
• preparation,
• substance,
• remedy,
• anaesthetic,
• agonist,
• medicine,
• antipyretic,
• peptide,
• opiate,