Serum barbiturates

The long-term use of phenytoin, phenobarbital, or primidone can disturb vitamin D and calcium metabolism and may result in osteomalacia. There are a few reports of patients taking vitamin D supplements who responded poorly to vitamin replacement while taking phenytoin or barbiturates. Serum phenytoin levels are not altered by vitamin D. 

The analysis of clinical samples is often complicated by the complexity of the sample matrix, which may contribute a significant background absorption at the desired wavelength. The determination of serum barbiturates provides one example of how this problem is overcome. The barbiturates are extracted from a sample of serum with CHCI3, and extracted from the CHCI3 into 0.45 M NaOH (pH 13). The absorbance of the aqueous extract is measured at 260 nm and includes contributions from the barbiturates as well as other components extracted from the serum sample. The pH of the sample is then lowered to approximately 10 by adding NH4CI, and the absorbance remeasured. Since the barbiturates do not absorb at this pH, the absorbance at pH 10 is used to correct the absorbance at pH 13 thus... 

The use of SPME for CE has not (yet) been studied widely. Li and Weber (170) reported an off-line SPME-CE approach for the determination of barbiturates in urine and serum, utilizing a sorbent of plasticized PVC coated around a stainless steel rod. Eor extraction, the coated rod was inserted for 4 min in a Teflon tube containing 50 p.1 of sample, and next the rod was repeatedly desorbed in another Teflon tube which each time contained 5 p.1 of desorption solution. This solution was transferred to an injection vial and an aliquot was injected into the CE system (Eigure 11.19). The extraction procedure appeared to be selective and effectively allowed the handling of very small samples. 

When two antiarrhythmic dragp are administered concurrently the patient may experience additive effects and is at increased risk for drug toxicity. When quinidine and procainamide are administered with digitalis, tiie risk of digitalis toxicity is increased. Hiarmacologic effects of procainamide may be increased when procainamide is administered with quinidine When quinidine is administered with the barbiturates or cimetidine, quinidine serum levels may be increased. When quinidine is administered with verapamil, there is an increased risk of hypotensive effects. When quinidine is administered with disopyramide, there is an increased risk of increased disopyramide blood levels and/or decreased serum quinidine levels. 

Fludrocortisone is contraindicated in patients with hypersensitivity to fludrocortisone and those with systemic fungal infections. Fludrocortisone is used cautiously in patients with Addison s disease infection, and during pregnancy (Pregnancy Category C) and lactation. Fludrocortisone decreases the effects of the barbiturates, hydantoins, and rifampin. There is a decrease in serum levels of the salicylates when those agents are administered with fludrocortisone... 

Thormartn, W., Meier, R, Marcolli, C., and Binder, F., Analysis of barbiturates in human serum and urine by high-performance capillary electrophoresis-micellar electrokinetic capillary chromatography with on-column multiwavelength detection, /. Chromatogr., 545, 445, 1991. 

The resulting product (II) is subsequently coupled to bovine-serum-albumin in a glycerol-w ater mixture in the presence of dicyclohexylcarbodiimide. The mixture is incubated overnight at 4°C, and the protein-hapten complex is dialysed against distilled water thereby causing its purification. Conjugation of the respective barbiturate to the protein carrier, comparison of the barbiturate BGG-conjugate to control BGG-solution and preparation of 14C-pentobarbital sodium are carried out respectively. 

Preparation of Antiserum The barbiturate-bovine-serum-albumin conjugate is duly emulsified with an equal volume of complete Freund s adjuvant and New Zealand albino rabbits are subsequently im-... 

For most of the applications outlined in Table 6, high precisions have been obtained. For example, for the determination of barbiturates in human serum, the intra-day precision for spiked serum samples was better than 2%, and the inter-day precision better than 5%7 Figure 15 shows the chromatograms of a blank and a spiked serum sample. 

CEC separation of barbiturates Determination of barbiturates in human serum... 

Olesen, 0. V., Determination of phenobarbital in serum in the presence of other barbiturates, sulphonamides, salicylates and other interfering drugs. Scand. J. Clin. Lab. Invest. 20, 109-112 (1967). 

Monitoring Perform baseline and follow-up LFTs (10 to 14 days) to detect hepatic dysfunction resulting from therapy. Perform a CBC and serum chemistries. Dependence and addiction Alcoholism may accompany or be followed by dependence on narcotics or sedatives. Barbiturates have been coadministered with disulfiram without untoward effects, but consider the possibility of initiating a new abuse. 

During the acute phase of thyrotoxicosis, B-adrenoceptor blocking agents without intrinsic sympathomimetic activity are extremely helpful. Propranolol, 20-40 mg orally every 6 hours, will control tachycardia, hypertension, and atrial fibrillation. Propranolol is gradually withdrawn as serum thyroxine levels return to normal. Diltiazem, 90-120 mg three or four times daily, can be used to control tachycardia in patients in whom blockers are contraindicated, eg, those with asthma. Other calcium channel blockers may not be as effective as diltiazem. Adequate nutrition and vitamin supplements are essential. Barbiturates accelerate T4 breakdown (by hepatic enzyme induction) and may be helpful both as sedatives and to lower T4... 

This technique can be also applied when the water-miscible acetonitrile is added to the serum sample for extracting the analytes. Following the addition of acetonitrile, the solution is saturated with potassium chloride so that the water and acetonitrile phases separate and derivatization is performed in the acetonitrile layer. Such alkylating procedures have been applied for prechromatographic derivatization of various drug residues with carboxylic groups, including penicillins (252) and barbiturates (253). 

A number of methods have been reported recently for the gas chromatographic separation of nonderivatized "free" barbiturates. The method (35) below is applicable to the qualitative and quantitative analysis of barbiturates, glutethimide and Dilantin from serum. It is a simple, rapid but accurate procedure using only 3 cm of serum. Dilantin could be separated on the same column as the barbiturates after it had been converted to its methylated derivative. 

RECOVERY AND REPRODUCIBILITY. Recovery of the individual barbiturates and glutethimide added to serum in concentrations of 10, 20, 50, and 100 mg/ varied from 95 - 102%. Recovery of Dilantin added to serum in concentrations of 5, 10, 30, and 50 mg/ is 90/98%. Retention time for Dilantin is 4.8 min with the conditions described above. 

The uses of constant-current coulometry for the determination of drugs in biological fluids are few, basically due to sensitivity restriction. Monforte and Purdy [46] have reported an assay for two allylic barbituric acid derivatives, sodium seconal and sodium sandoptal, with electrogenerated bromine as the titrant and biamperometry for endpoint detection. Quantitative bromination required an excess of bromine hence back titration with standard arsenite was performed. The assay required the formation of a protein-free filtrate of serum with tungstic acid, extraction into chloroform, and sample cleanup by back extraction, followed by coulometric titration with electrogenerated bromine. The protein precipitation step resulted in losses of compound due to coprecipitation. The recoveries of sodium seconal and sodium sandoptal carried through the serum assay were approximately 81 and 88%, respectively. Samples in the concentration range 7.5-50 pg/mL serum were analyzed by this procedure. 

Amobarbital is a barbituric acid derivative of intermediate duration of action. It is administered orally in doses of 15 to 200 mg as a sedative hypnotic and in ampoules of 65 to 500 mg for intravenous and intramuscular injection for the seizure control.6 Following a single oral dose of 120 mg, peak serum concentrations averaged 1.8 mg/L after 2 h.7 After an oral dose of 600 mg distributed over a 3-h period, the peak blood concentration was achieved after 30 min, averaging 8.7 mg/L, with a decline to 4.1 mg/L by 18 h.6... 

Phenobarbital is utilized as a daytime sedative and anticonvulsant. It also induces several cytochrome P450 isozymes. Compared to other barbiturates, phenobarbital has a low oil/water partition coefficient, which results in slow distribution into the brain. It is available for oral, intravenous, or intramuscular administration. Doses for epileptic patients range from 60 to 200 mg per day. After a single oral dose of 30 mg, peak serum concentrations averaged 0.7 mg/L (n = 3). Repeated doses over a period of 7 days resulted in an average peak concentration of 8.1 mg/L.6 Chronic administration of 200 mg per day as anticonvulsant medication resulted in an average blood concentration of 29 mg/L (range = 16 to 48 mg/L).8... 

After the September 11, 2001, terrorist attacks in the United States, federal investigators discussed the use of truth serum to obtain information from jailed terrorism suspects. The serum is the barbiturate thiopental, which is also known as pentothal sodium. The use of this drug to make a reluctant person talk has been portrayed in movies, books, and on television. 

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