Barbiturates into

The same procedure has been applied for resolution of mephenytoin and some barbiturates into enantiomers (26). 

Zukowski, J. Sybilska, D. Bojarski, J. Szejtli, J. Resolution of chiral barbiturates into enantiomers by reversed-phase high-performance hquid chromatography using methylated P-cyclodextrins. J. Chromatogr. 1988,463 (3), 381-390. 

For GC analysis, extraction of the analyte from the sample is often necessary. For example, to extract barbiturates from serum, the serum first is acidified to convert the barbiturates into a form soluble in an organic solvent, such as dichloromethane. A volume of this solvent then is shaken vigorously with the acidified serum. When the aqueous and organic layers separate, most of the barbiturates are present in the organic phase, and many interferences, such as proteins, remain in the aqueous phase. Solvent extraction is also frequently used to increase the concentration of an analyte before chromatographic analysis. 

Barbiturates S Ultraviolet spectrophotometry Extract barbiturate into CHCI3, back-extract into NaOH solution, and measure UV absorption at alkaline pH at 252 nm... 

The body also has a blood-brain barrier that enables only lipid soluble dmgs—such as general anesthetics and barbiturates— into the brain and cerebral spinal fluid (CSF). The only way for nonlipid soluble dmgs to enter the brain is if they are instilled intrathecally, that is, injected directly into the CSF, bypassing the blood-brain barrier. 

Substitution of the 2-oxygen by sulphur converts barbiturates into highly lipophilic, potent hypnotics, with a rapid onset of action and short duration of activity. A notable example of this class is thiopentone (XXIV, thiome-bumal, thiopental, Nesdonal, Penthiobarbital, Pentothal), which is widely employed as an intravenous anaesthetic. 

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... 

Cyanide compounds are classified as either simple or complex. It is usually necessary to decompose complex cyanides by an acid reflux. The cyanide is then distilled into sodium hydroxide to remove compounds that would interfere in analysis. Extreme care should be taken during the distillation as toxic hydrogen cyanide is generated. The cyanide in the alkaline distillate can then be measured potentiometricaHy with an ion-selective electrode. Alternatively, the cyanide can be determined colorimetricaHy. It is converted to cyanogen chloride by reaction with chloramine-T at pH <8. The CNCl then reacts with a pyridine barbituric acid reagent to form a red-blue dye. 

Most drugs in the pyrimidine series fall into four categories the barbiturates, the sulfonamides, the antimicrobials and the antitumour agents. In addition there are innumerable pyrimidines with diverse biological activities, some of which are in use. 

Rotenone is a common insecticide that strongly inhibits the NADH-UQ reductase. Rotenone is obtained from the roots of several species of plants. Tribes in certain parts of the world have made a practice of beating the roots of trees along riverbanks to release rotenone into the water, where it paralyzes fish and makes them easy prey. Ptericidin, Amytal, and other barbiturates, mercurial... 

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. 

Preparation of Sodium 1-Methyl-5-Allyl-5-(1-Methyl-2-Pentynyl) Barbiturate A solution of 61 g of 1-methyl-5-allyl-5-(1-methyl-2-pentynyl) barbituric acid in 100 ml of ether was extracted with 465 ml of 2% aqueous sodium hydroxide solution. The aqueous extract was washed with successive 75 ml and 50 ml portions of ether. The pH of the aqueous solution was adjusted to 11.7, using 5% aqueous sodium hydroxide solution. 5 g of decolorizing carbon were added to the solution with stirring the mixture was permitted to stand for 20 minutes at room temperature, and the carbon was removed by filtration. A solution containing 4 g of sodium carbonate in 25 ml of water was added to the aqueous solution, and the mixture was filtered sterile through a porcelain filter candle of 02 porosity into sterile bottles. The aqueous solution was then dried from the frozen state, whereupon a sterile residue of sodium 1-methyl-5-allyl-5-(1-methyl-2-pentynyl) barbiturate, weighing about 62 g was obtained. 

Parts of diallyl-barbituric acid are added to a precooled mixture of 1 5.5 parts of concentrated sulfuric acid and 0.5 part of water while stirring intensively, the mixture being cooled so that its temperature does not exceed 25°C. The honey-colored viscous solution Is stirred vigorously and all at once into 45 parts of water, whereupon the mixture warms up to 35°C to 40°C and, after several seconds, solidifies into a thick pulp, which Is then heated as quickly as possible to 95°C, at which temperature a clear solution Is formed. This is cooled slowly until the 5-allyl-5-((3-hydroxypropyl)-barbituric acid begins to form coarse-grained crystals, after which the mass is cooled rapidly to 20°C. 

The thus-washed crude product is dissolved in a mixture of 12 parts of ethanol and 20 parts of benzene, with mild warming if necessary. 1 Part of sodium chloride and 1.5 parts of saturated aqueous sodium chloride solution are added to the obtained solution in ethanol-benzene, and whole thoroughly admixed. When the brine layer has settled. It is separated and the afore-described washing repeated. The clear solution is concentrated under reduced pressure until incipient formation of crystals and is then poured into 30 parts of benzene, whereupon a thick crystalline pulp is forthwith formed which, after being cooled to room temperature, is centrifuged off. The so-obtained 5-allyl-5-( 3-hydroxypropyl)-barbituric acid is dried at 70°C under reduced pressure and can be used for therapeutic purposes without further purification. Melting point 164 °C to 165°C. Yield 5 parts. 

The other method used is infusion of intravenous anaesthetics such as propofol, etomidate (for induction) and the barbiturates such as thiopental and pentobarbital. Investigations into the mechanism of anaesthesia have made use of all these compounds in order to identify a common mode of action linked to likely mechanisms within the CNS. 

Sedatives and hypnotics may be divided into two classes barbiturates and miscellaneous sedatives and hypnotics. The barbiturates are divided into several groups, depending on tiieir duration of action ... 

All dragp entering the body ultimately leave the body. Some leave virtually unchanged, whereas others are transformed into other, less-potent chemicals or compounds detoxified (to make nontoxic or not harmful) before they are eliminated. Barbiturates and miscellaneous sedatives and hypnotics are detoxified by the liver... 

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). 

OWENS has prepared antibodies to PCP in goats. When administered to mice the PCP levels in blood rose tenfold as an antibody-bound form that was readily excreted in urine. BROWNE tested the selfadministration by rats of 1,000 compounds related (and not related) to PCP, some of which produced PCP-like effects. One compound that was self-administered prevented the entrance of PCP into brain. BALSTER gave a general review of the effects produced by PCP in laboratory animals and showed that some effects were similar to those produced by amphetamine, some to barbiturates, and some to antipsychotics. This response profile makes PCP a unique drug that stands alone in its complex effects and toxicity. 

The major inhibitory neurotransmitter in the cerebral cortex is y-aminobutyric acid (GABA). It attaches to neuronal membranes and opens chloride channels. When chloride flows into the neuron, it becomes hyperpolarized and less excitable. This mechanism is probably critical for shutting off seizure activity by controlling the excessive neuronal firing. Some antiepileptic drugs, primarily barbiturates and benzodiazepines, work by enhancing the action of GABA. 

In late teens into mid-twenties, heavy abuse of stimulants, barbiturates, and alcohol currently smokes marijuana three times per week and states "it calms me down and helps me sleep" occasionally drinks on weekends... 

P.O.64 is synthesized by diazotization of 5-amino-6-methylbenzimidazolone and subsequent coupling of the diazonium component onto barbituric acid. The pigment, recently introduced into the market, affords a yellowish orange shade. 

---