Hello,
Endocet ideally should not be combined with other sleeping pills or sedatives or tranquilizers unless it is prescribed by the concerned physician.
Endocet is a combination of two painkillers-acetaminophen(commonly know as paracetmol or crocin) and oxycodone which is a narcotic analgesic.Oxycodone causes dependence (habit forming).
As far as safety is concerned,if the combination of endocet and rozerem hasn't been prescribed by the doctor it is not safe.The level of sedation caused by the combination of the two drugs is very dangerous.
I would suggest you to get him a checkup that will help decide his dependence and better options for dealing with sleep apnea.Hope this has been useful.
