Verapamil or Covera-HS is a calcium channel blocker with a bed time dosing formulation.
Blood vessels have calcium channels or "pathways" in their walls. Calcium moves along these channels being involved in blood vessel constriction. The calcium channel blocker, Verapamil or Covera-HS, affects how calcium moves along these channels resulting in relaxed blood vessel walls and reduced blood pressure.
This special formulation provides peak concentration in the morning when blood pressure and heart rate are the highest and people are most vulnerable to chest pain and heart attack. It is a controlled release formulation which releases the Verapamil or Covera-HS 4-5 hours after ingestion, so that peak effects are between 6 am and noon. It starts to work about 3 hours before getting up.
FDC Reports 1996;58(10):T&G-7
Am J Cardiology 1995;75:1102
The relevant product monographs must be regarded as the appropriate sources of prescribing information.