Barbiturates drug interactions

The most common unwanted effects of the barbiturates are oversedation and psychomotot impaitment, which may petsist well into the next day following a hypnotic dose. Patadoxical excitement, hypersensitivity reactions, and muscle or joint pain may occur in rare cases. Drug-drug interactions occur with the CNS sedatives, and a number of drugs have enhanced metabolism when co-administered with barbiturates (Barnhill et al. 1989). 

Geriatric Considerations - Summary Because barbiturates have a low therapeutic window, a wide range of drug interactions and rapid development of folerance, great potential for abuse and dependence, fhese agents are not recommended for use in older adulfs. 

Because most antidepressants require oxidative metabolism as a necessary step in their elimination, they can be the target of a pharmacokinetic drug-drug interaction, as well as the cause. The CYP enzymes mediating the biotransformation of the various antidepressants are also shown in Table 7-30. CYP 1A2 and 3A3/4 are induced by anticonvulsants such as barbiturates and carbamazepine. As expected, coadministration of these anticonvulsants has been shown to lower plasma levels of TCAs and would be predicted to have the same effect on nefazodone, sertraline, and venlafaxine. 

Valerian (Valerian officinalis). No drug interactions have been reported, but animal studies suggest that valerian, used as a sedative and sleep aid, might increase the effects of barbiturates such as pentobarbital, hexo-barbital, and thiopental. 

Drug interactions include rise in plasma concentration when concomittant administration with cimetidine and lowering of the concentration with barbiturates, phenytoin, rifampin. Digoxin levels may be variably affected, can rise. 

Use of barbiturates combined with many other medications has been reported to alter the effects of barbiturates or the other drugs. Most of these drug interactions have been specifically reported with the barbiturate phenobarbital. There are... 

Nifedipine was one of the first CYP3A4 substrates to be identified (167,168) and has been the subject of a large number of drug-drug interaction studies both in vitro and in vivo. Pharmacokinetic studies with nifedipine clearly identify inhibitors, such as itraconazole (169) and grapefruit juice (170), and inducers, such as the barbiturates (171) and rifampin (172). 

SULPHONYLUREAS BARBITURATES 1 hypoglycaemic efficacy Plasma levels of sulphonylureas are 1 by induction of CYP-mediated metabolism Watch for and warn patients about symptoms of hyperglycaemia - For signs and symptoms of hyperglycaemia, see Qinical Features of Some Adverse Drug Interactions, Hyperglycaemia... 

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