Barbiturates barbital

The concentration of the barbiturate barbital in a blood sample was determined by extracting 3.00 mL of the blood with 15 mL of CHCI3. The chloroform, which now contains the barbital, is then extracted with 10.0 mL of 0.045 M NaOH (pH = 13). A 3.00-mL sample of the aqueous extract is placed in a 1.00-cm cell, and an absorbance of 0.115 is measured. 

Barbiturates Barbital, allobarbital, phenobarbital, butalbital Jones et al. (2003)... 

Barbiturates. The hrst barbiturate, barbital, was introduced in 1903 and was followed a few years later by phenobarbital. The barbiturates effectively relieve anxiety, but they are never used as anxiolytics today due to toxicity and abuse concerns. However, several barbiturates, including phenobarbital (Luminal), secobarbital (Seconal), and pentobarbital (Nembutal), remain available and are occasionally used to treat epilepsy and rarely to manage acute alcohol withdrawal. 

Barbiturates. The first barbiturate, barbital, was introduced at the turn of the 20th century. Hundreds of others, including phenobarbital and pentobarbital, were later developed. The barbiturates were a highly successful class of medications as it became clear that they treated not only alcohol withdrawal but seizure disorders, anxiety, and insomnia as well. By the 1960s, however, the barbiturates were largely surpassed by the benzodiazepines. The newer benzodiazepines act in a similar fashion and provide much the same therapeutic benefit but are significantly safer and easier to tolerate. 

Schedule IV. These drugs supposedly have a lower potential for abuse than schedule III drugs, with only a limited possibility of physical dependence, psychologic dependence, or both. Examples include certain antianxiety drugs (meprobamate), certain barbiturates (barbital, phenobarbital), and a variety of other depressants and stimulants. 

Barbiturates -barbital Phenobarbital, secobarbital Sedative-hypnotic (6), antiseizure [9], anesthetic (11]... 

Barbiturates Barbital, phenobarbital Separated on a C-18 high carbon loaded silica column mobile phase methanol-water detected by UV at 254 nm... 

This is an Australasian shrubby pepper Piper methysticum). Amidst much ceremony, its crushed roots are made into an intoxicating beverage by the peoples of the Molucca Islands and the Northern coast of Australia. Kava is usually recommended for anxiety. Kava has sedative and extrapyramidal effects, in common with some anticholinergic and antidopaminergic drugs, and probably has synergistic sedative effects when administered with benzodiazepines, barbiturates (barbitals), alcohol. 

Thomapyrin containing acetaminophen, caffeine and acetylsalicylic acid Antiviral drug suramin Amino group containing drugs codeine phosphate, ephedrine hydrochroride, thebaine, berberine, hydrochloride, jatrorrizine hydrochloride, cocaine hydrochloride Isradepin and by-products Morphine alkaloids Barbiturates (barbital, phenobarbital, secobarbital, thiopental)... 

Barbiturates (Veronal. Barbital, Luminal, Amytal), ethyl orthoformate, and other chemicals are produced commercially from sodium ethoxide. 

The structure of barbituric acid was the subject of disagreement for many years, but since 195 2 (52BSB44) the trioxo formulation (57 R = H) has been accepted generally, along with the fact that barbituric acid loses a proton, first from carbon (anion) and subsequently from nitrogen (dianion). Barbital (5,5-diethylbarbituric acid) adopts a similar trioxo form (57 R = Et) (69AX(B)1978). 

Death from overdose of barbiturates may occur and is more likely when more than 10 times the hypnotic dose is ingested. The barbiturates with high lipid solubility and short half-lives are the most toxic. Thus the lethal dose of phenobarbital is 6—10 g, whereas that of secobarbital, pentobarbital, or amo-barbital is 2-3 g. Symptoms of barbiturate poisoning include CNS depression, coma, depressed reflex activity, a positive Babinski reflex, contracted pupils (with hypoxia there may be paralytic dilation), altered respiration, hypothermia, depressed cardiac function, hypotension, shock, pulmonary complications, and renal failure. 

Bamiphylline, 426 Bamipine, 51 Barbital, 267, 268 Barbiturates, listing, 268, 269 Baroreceptors, 54 Bayer-Villiger lactone synthesis, 28, 31... 

The preparation of barbiturates illustrates many of the synthetic methods covered in this chapter. The preparation employs the reaction of urea (C0(NH2)2) with malonic ester to form barbituric acid. The general reaction is presented in Figure 15-30. The stable pyrimidine and other resonance forms help drive the reaction. By alternating the substituent at carbon number five (C5), various pharmacologically active substances can be formed. Barbital, a sedative, and phenobarbital, a sleeping aid, are shown in Figure 15-31. 

The barbiturates were widely used as sedative-hypnotic drugs. Barbital was introduced as a drug in 1903. The method of synthesis for thousands of its analogs has undergone little change. Urea reacts with various derivatives of malonic acid, usually a diethyl ester of a dialkyl substituted malonic acid. This is a classic example of a nucleophilic acyl substitution. A derivative of ammonia reacts with esters to form an amide, only in this case a cyclization to a strainless six-membered ring results because of the proximity of the bifunctionality. 

The CNS depressants include barbiturates, nonbarbiturate sedatives, and the benzodiazepines. As the medical use of barbiturates decreased, primarily because of their high addiction liability and the danger of acute lethality, the use of the benzodiazepine anxiolytics increased. The most commonly abused barbiturates are secobarbital, pentobarbital, and amobarbital. Pheno-barbital is not generally abused, because of its slow onset of action. The most commonly abused anxiolytics include diazepam, chlordiazepoxide, midazolam, lo-razepam, and flurazepam. These drugs are readily attainable from illicit sources. 

Historically, alcohol has been used as an anxiety-reducing agent, both casually and in professional medical settings. In 1903, barbital was introduced as the first barbiturate to treat anxiety, and phenobarbital followed a few years later. Barbiturates have many side effects and addictive properties, and overdose can lead to coma and death. For these reasons, they are rarely used today, except to treat some forms of epilepsy. This class of drugs was eventually replaced by the benzodiazepines (see Chapter 4). 

The four derivatives of barbituric acid clinically useful as antiseizure drugs are phenobarbital, mephobarbital, metharbital, and primidone. The first three are so similar that they are considered together. Metharbital is methylated barbital, and mephobarbital is methylated phenobarbital both are demethylated in vivo. The pKas of these three weak acid compounds range from 7.3 to 7.9. Slight changes in the normal acid-base balance, therefore, can cause significant fluctuation in the ratio of the ionized to the un-ionized species. This is particularly important for phenobarbital, the most commonly used barbiturate, whose pKa is similar to the plasma pH of 7.4. 

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