Drug hypersensitivity barbiturates

The barbiturates are contraindicated in patients with known hypersensitivity to the drugs. The barbiturates are used cautiously in patients with liver or kidney disease and those with neurological disorders. The barbiturates (eg, phenobarbital) are used with caution in patients with pulmonary disease and in hyperactive children. When barbiturates are used with other CNS depressants (eg, alcohol, narcotic analgesics, and antidepressants), an additive CNS depressant effect may occur. See Chapter 26 for additional information on the barbiturates. 

BARBITURATES The barbiturates can produce a hypersensitivity rash. Should a skin rash occur, the nurse must notify the primary health care provider immediately because the primary health care provider may discontinue the drug. The nurse carefully examines all affected areas and provides an accurate description. If pruritus is present, the nurse keeps the patient s nails short, applies an antiseptic cream (if prescribed), and tells the patient to avoid the use of soap until the rash subsides. 

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). 

Hypersensitivity Hypersensitivity to anticholinergic drugs. Patients hypersensitive to belladonna or to barbiturates may be hypersensitive to scopolamine. 

Among the drugs which are known to interact with barium, the barbiturates sodium pentobarbital and phenobarbital were found to have an increased depressive effect on the hearts of rats exposed to barium (Kopp et al. 1985 Perry et al. 1983, 1989). This hypersensitivity of the cardiovascular system to anesthesia was not observed in similarly treated animals that were anesthetized with xylazine plus ketamine. Results of the study indicated that the hypersensitivity was specific to the barbiturates and not a generalized effect of anesthesia (Kopp et al. 1985). 

Drug interactions May decrease antihypertensive effects of ACE inhibitors, angiotensin II antagonists. May decrease antihypertensive and diuretic effects of thiazide and loop diuretics May decrease absorption of vitamin B,2 Effects decreased by barbiturates, phenytoin, and rifampin decreases effect of salicylates and vaccines Decreases clearance of beta-lactams Risk for hypersensitivity increased in patients who are on thiazides or ACE inhibitors and allopurinol... 

Hypersensitivity to barbiturates can result in a life-threatening syndrome called the Drug, Rash with Eosinophilia and Systemic Symptoms (DRESS) Syndrome with a mortality of 10%. In persons developing hypersensitivity to barbiturates, there is a potential of cross-sensitivity with other aromatic antiepileptics, such as phenytoin and carbamazepine. 

Eighty-three patients provided concentration-time data. Exclusion criteria included elevated transaminases, bilirubin, or serum creatinine decreased neutrophils, hemoglobin, or platelet counts malabsorption syndrome opportunistic infections alcohol, narcotics, barbiturates, cocaine, or other CNS-active substance abuse hypersensitivity to any of the protocol mandated drugs patients of childbearing potential who were unwilling to use an effective method of contraception and concomitant medications interfering with human cytochrome P450 system. 

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