Drugs phenobarbital

Sullivan, F.M. and McElhatton, P.R. (1975) Teratogenic activity of the antiepileptic drugs phenobarbital, phenytoin, and primidone in mice. Toxicol Appl Pharmacol 24 271—282. 

The water-soluble metabolites of sedative-hypnotics, mostly formed via the conjugation of phase I metabolites, are excreted mainly via the kidney. In most cases, changes in renal function do not have a marked effect on the elimination of parent drugs. Phenobarbital is excreted unchanged in the urine to a certain extent (20-30% in humans), and its elimination rate can be increased significantly by alkalinization of the urine. This is partly due to increased ionization at alkaline pH, since phenobarbital is a weak acid with a pKa of 7.4. 

Figure 5.34 Mechanism of induction of CYP2B6 by a chemical such as the drug phenobarbital. This drug activates a nuclear receptor (CAR).This combines with the retinoid X receptor and binds to PBREM, as specific section of the CYP gene, which stimulates the production of CYP2B6 mRNA leading to the production of CYP2B6 protein and enzyme. Abbreviations CAR, constitutive androstane receptor RXR retinoid X receptor PBREM, phenobarbital-responsive enhancer module.

Acidic and basic drugs (phenobarbital, diazepam, methaqualone, testosterone, cannabinol, testosterone propionate, 9-tetrahydro-cannabinol, 9-tetrahydrocannabinolic acid) CEC Hypersil C8 Acetonitrile-50 mAf phosphate buffer, pH 2.5 (60 40) with 2 pl/ml hexylamine for 1 min, then linear gradient to acetonitrile-25 mM phosphate buffer with 2 pl/ml hexylamine (75 25) 340 mm x 100 pm i.d. 250 mm to the detector, stepped gradient, comparison with MECC... 

Ratio of lethal dose to effective dose for morphine (an opioid, Chapter 14), chlorpromazine (a neuroleptic, Chapter 13), and the anxiolytic, hypnotic drugs, phenobarbital and diazepam. 

Compounds which are primarily sedative or central depressant also have found use in treating hypertension. In this category, one might include mebuta-mate (5, 9), a molecular modification of the carisoprodol and meprobamate family of compounds. These molecular modifications have coursed through the fields of tranquilizers, muscle relaxants, and most recently, antihypertensive drugs. The relatively old drug, phenobarbital, has been used as a central depressant component in a number of antihypertensive combination products. 

Soon after its introduction as a hypnotic drug, phenobarbital was found to be an excellent antiepileptic drag. Historically, agents introduced for the treatment of epilepsy are also turned to for psychiatric indications. The original first generation antiepileptic drag, a bromide salt, which appears in 1857, was also known for its tranquilizing... 

Long Acting Barbital P henobarbital Duration 10-12 hours. Barbital is excreted primarily by the kidneys. Phenobarbital is metabolized by the P450 enzymes in the liver. Phenobarbital induces P450 enzymes, causing increased metabolism of many drugs. Phenobarbital is used clinically as an anticonvulsant. ... 

Casamenti et al. [1399] developed a method for screening 11 central nervous system drugs (phenobarbital, olanzapine, clozapine, risperidone, loxapine, haloperidol, imipramine, amitriptyline, fluoxetine, chlorpromazine, paroxetine) on a Cjg column (A = 230 nm) using a 20/11.7 water (0.4g tetramethylammonium perchlorate with 0.2 mL of 7% (m/m) HCIO4 to pH 2.8 with ammonia)/acetonitrile mobile phase. Keep in mind that perchlorates, when concentrated with some metals, are hazardous. Elution was complete in 35 min with good resolution for most compounds. Plots of the effects of mobile phase modifier level and percent acetonitrile on overall retention are presented. Linear ranges of 25-5000 ng/mL with detection limits of 10-250 ng/mL (analyte dependent) are reported. 

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