How does Cardizem (Diltiazem) affect sleep?

Effects of Cardizem (Diltiazem) on Sleep

Diltiazem may cause next-day somnolence and potentially disrupt normal sleep patterns, particularly when used concomitantly with other medications that affect sleep or are metabolized through the CYP3A4 pathway. 1

Direct Effects on Sleep

• Diltiazem has been shown to potentiate sleep-inducing effects when combined with other medications, suggesting it may have sleep-modifying properties 2
• When combined with serotonergic agents, diltiazem can significantly increase total sleep time and slow-wave sleep while decreasing REM sleep 2
• The medication affects neuronal circuits in the brain that regulate sleep, particularly the ventrolateral preoptic nucleus (VLPO) and tuberomammillary nucleus (TMN) pathways 2

Drug Interactions Affecting Sleep

• Diltiazem is a moderate CYP3A4 inhibitor, which can increase plasma concentrations of medications metabolized through this pathway, including sleep medications 3
• A case report documented significant next-day somnolence in an elderly patient taking suvorexant (a sleep medication) concomitantly with diltiazem, even when the medications were taken at different times of day 1
• The interaction resulted in the patient being unable to wake up in the morning and oversleeping by approximately 3 hours 1

Timing of Administration and Sleep Effects

• Studies comparing morning versus evening dosing of diltiazem found no significant difference in cardiovascular efficacy between dosing times 4
• This suggests flexibility in administration timing, which may help minimize sleep disruption if a patient experiences sleep-related side effects 4
• Unlike some cardiovascular medications that have pronounced circadian effects, diltiazem appears to maintain consistent therapeutic action regardless of administration time 4

Potential Neurological Side Effects Affecting Sleep

• Long-term use of diltiazem has been associated with myoclonus (involuntary muscle jerking) in some patients, which could potentially disrupt sleep 5
• In one documented case, a patient developed myoclonus after years of diltiazem therapy, with symptoms that included abnormal sensations and body movements that were sometimes triggered by exaggerated startle responses 5
• These movement-related side effects could potentially interfere with sleep initiation or maintenance 5

Clinical Considerations

• Diltiazem is not listed among recommended or non-recommended medications for treating insomnia in clinical practice guidelines 3
• When prescribing diltiazem to patients with sleep concerns, clinicians should monitor for potential drug interactions, especially with medications metabolized by CYP3A4 3
• For patients experiencing sleep disturbances while taking diltiazem, consider:
  • Adjusting the timing of administration 4
  • Evaluating for potential drug interactions 1
  • Monitoring for neurological side effects that may disrupt sleep 5

Special Populations

• Elderly patients may be particularly susceptible to sleep disturbances from diltiazem, especially when combined with other medications 1
• In these cases, switching to a different calcium channel blocker or to a medication not metabolized by CYP3A4 may be necessary 1