ICD-10-CM > S00-T88 > T36-T50 > T46 > T46.1 > T46.1X > T46.1X6 T46.1X6 Underdosing of calcium-channel blockers Non-Billable/Non-Specific Codes T46.1X6A..., initial encounterT46.1X6D..., subsequent encounterT46.1X6S..., sequela