title: Induced next-day somnolence in an elderly patient taking suvorexant concomitantly with diltiazem.
abstract: OBJECTIVE
  To present the first case of induced next-day somnolence in a patient taking suvorexant concomitantly with diltiazem.
  
  
  METHODS
  The patient was an 88-year-old female who had suffered from insomnia and anorexia, for which a psychiatric clinic had prescribed 1.5 mg/day aripiprazole and 15 mg/day suvorexant (both once daily at bedtime), which cured her insomnia. Subsequently, a different hospital prescribed diltiazem hydrochloride (100 mg, sustained-release, daily after breakfast) for treatment of hypertension. After starting diltiazem, the patient was unable to wake up in the morning and overslept by ~ 3 hours. On the third day of taking diltiazem, the patient, on the basis of her own judgment, took only half a tablet of suvorexant, and found that she was able to sleep, and there was no somnolence the following morning. As halving suvorexant tablets is an off-label usage, and lower-dose tablets are not available, her prescription was switched to 1-mg rilmazafone hydrochloride. Since then, her sleep disorder has not recurred.
  
  
  CONCLUSIONS
  Because suvorexant is metabolized by CYP3A4, next-day somnolence could have occurred as a result of increased plasma suvorexant concentration due to CYP3A4 inhibition by diltiazem.
  
  
  CONCLUSIONS
  Elderly patients may suffer next-day somnolence if they concomitantly take suvorexant and sustained-release diltiazem hydrochloride, even if the diltiazem dose is low and there is a significant interval between the administration times of the two drugs. In order to avoid drug interaction, it may be desirable to switch from suvorexant to a different soporific that is not metabolized by CYP3A4.
authors.forename: Atsuko
authors.initials: A
authors.lastname: Shihyakugari
authors.forename: Satoko
authors.initials: S
authors.lastname: Hori
authors.forename: Akiko
authors.initials: A
authors.lastname: Miki
authors.forename: Yasufumi
authors.initials: Y
authors.lastname: Sawada
mesh_terms: D000369:Aged, 80 and over; D001381:Azepines / Q000009:adverse effects*; D004110:Diltiazem / Q000009:adverse effects*; D004347:Drug Interactions; D005260:Female; D006801:Humans; D000068776:Sleep Aids, Pharmaceutical / Q000009:adverse effects*; D012893:Sleep Wake Disorders / Q000139:chemically induced*; D014230:Triazoles / Q000009:adverse effects*
chemical_list: D001381:Azepines; D000068776:Sleep Aids, Pharmaceutical; D014230:Triazoles; C551624:suvorexant; D004110:Diltiazem