To assure the safe and effective use of ProSom, the following information and instructions should be given to patients:
1. Inform your physician about any alcohol consumption and medicine you are taking now, including drugs you may buy without a prescription. Alcohol should not be used during treatment with hypnotics.
2. Inform your physician if you are planning to become pregnant, if you are pregnant, or if you become pregnant while you are taking this medicine.
3. You should not take this medicine if you are nursing, as the drug may be excreted in breast milk.
4. Until you experience the way this medicine affects you, do not drive a car, operate potentially dangerous machinery, or engage in hazardous occupations requiring complete mental alertness after taking this medicine.
5. Since benzodiazepines may produce psychological and physical dependence, you should not increase the dose before consulting your physician. In addition, since the abrupt discontinuation of ProSom may be associated with temporary sleep disturbances, you should consult your physician before abruptly discontinuing doses of 2 mg per night or more.
If ProSom is given concomitantly with other drugs acting on the central nervous system, careful consideration should be given to the pharmacology of all agents. The action of the benzodiazepines may be potentiated by anticonvulsants, antihistamines, alcohol, barbiturates, monoamine oxidase inhibitors, narcotics, phenothiazines, psychotropic medications, or other drugs that produce CNS depression. Smokers have an increased clearance of benzodiazepines as compared to nonsmokers; this was seen in studies with estazolam.
While no in vivo drug-drug interaction studies were conducted between estazolam and inducers of CYP3A, compounds that are potent CYP3A inducers (such as carbamazepine, phenytoin, rifampin, and barbiturates) would be expected to decrease estazolam concentrations.
Estazolam Interaction with Drugs that Inhibit Metabolism via Cytochrome P450 3A (CYP3A): The metabolism of estazolam to the major circulating metabolite 4-hydroxy-estazolam and the metabolism of other triazolobenzodiazepines is catalyzed by CYP3A. Consequently, estazolam should be avoided in patients receiving ketoconazole and itraconazole, which are very potent inhibitors of CYP3A. With drugs inhibiting CYP3A to a lesser, but still significant degree, estazolam should be used only with caution and consideration of appropriate dosage reduction. The following are examples of drugs known to inhibit the metabolism of other related benzodiazepines, presumably through inhibition of CYP3A: nefazodone, fluvoxamine, cimetidine, diltiazem, isoniazide, and some macrolide antibiotics.
Drug Interaction with Fluoxetine: A multiple-dose study was conducted to assess the effect of fluoxetine 20 mg BID on the pharmacokinetics of estazolam 2 mg QHS after seven days. The pharmacokinetics of estazolam (Cmax and AUC) were not affected during multiple-dose fluoxetine, suggesting no clinically significant pharmacokinetic interaction.
Estazolam Interaction with Other Drugs that are Metabolized by Cytochrome P450 (CYP): At clinically relevant concentrations, in vitro studies indicate that estazolam (0.6µM) was not inhibitory towards the major cytochrome P450 isoforms CYP1A2, CYP2A6, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A. Therefore, based on these in vitro data, estazolam is very unlikely to inhibit the biotransformation of other drugs metabolized by these CYP isoforms.
Benzodiazepines may cause fetal damage when administered during pregnancy. An increased risk of congenital malformations associated with the use of diazepam and chlordiazepoxide during the first trimester of pregnancy has been suggested in several studies. Transplacental distribution has resulted in neonatal CNS depression and also withdrawal phenomena following the ingestion of therapeutic doses of a benzodiazepine hypnotic during the last weeks of pregnancy.
ProSom is contraindicated in pregnant women. If there is a likelihood of the patient becoming pregnant while receiving ProSom she should be warned of the potential risk to the fetus and instructed to discontinue the drug prior to becoming pregnant. The possibility that a woman of childbearing potential is pregnant at the time of institution of therapy should be considered.
Estazolam is contraindicated with ketoconazole and itraconazole, since these medications significantly impair oxidative metabolism mediated by CYP3A.