ICD-10-CM > S00-T88 > T36-T50 > T43 > T43.0 > T43.02 > T43.026 T43.026 Underdosing of tetracyclic antidepressants Non-Billable/Non-Specific Codes T43.026A..., initial encounterT43.026D..., subsequent encounterT43.026S..., sequela