The present invention pertains to a solid dosage form comprising an analgesically effective amount of opioid analgesic and an opioid abuse-deterring amount of a nontoxic N-methyl-D-aspartate receptor antagonist contained in a carrier which isolates, or separates, the antagonist from the opioid analgesic. The nontoxic N-methyl-D-aspartate receptor antagonist is released and made available only when the dosage form is misused, as would be the case when the dosage form is crushed or dissolved and thereafter administered in a manner other than that indicated, e.g., by injection or intranasally.