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Phenobarbital injectable forms

In a mixture of 35 % v/v water, 35 % v/v propylene glycol and 30 % v/v ethanol at a pH of 8.9, the solubility of phenobarbital at room temperature is approximately 11 % w/v. An example of a formula for a phenobarbital injection of 50 mg/mL is given in Table 18.11. The pH is usually adjusted to a value between 7 and 8. Phenobarbital in these injections is thus partially in the ionised form. The non-ionised form is dissolved by the organic solvents. [Pg.362]

Butyl derivatives make possible the resolution of compounds the methylation of which lead to the same derivatives [518]. They were prepared in an analogous manner, by injection of substrates with a 25% methanolic solution of tetra-n-butylammonium hydroxide into the injection port heated at 270°C. The analysis can be performed on 3% OV-17 at 220°C Fig. 5.31 illustrates an example of the separation of several barbiturates in the form of methyl and butyl derivatives. Mephobarbital and phenobarbital, which being methylated give rise to the same compound, could be resolved after their conversion into butyl derivatives in addition, the different retention times of the derivatives could be utilized for the identification of barbiturates. [Pg.183]

In the solid (crystalline) form the barbituric acid exists in the triketo or lactam form. In aqueous solution tautomerism to the enolic lactim occurs the enolic hydroxyl (at C-2) is acidic acid and is ionized according to the particular drug s pKa (e.g., pentobarbital = 8.0, phenobarbital = 7.5). Titrating such a solution with a stoichiometric equivalent of base such as NaOH will convert the lactam quantitatively to the barbiturate s sodium salt, which can be isolated. Many barbiturates are commercially produced both in the lactam and in the sodium enolate salt form. Of course, the salts are water soluble and thus are used to formulate injectable dosage forms including those for IV anesthetic use. [Pg.568]


See other pages where Phenobarbital injectable forms is mentioned: [Pg.137]    [Pg.99]    [Pg.24]    [Pg.68]    [Pg.92]    [Pg.374]    [Pg.49]    [Pg.69]    [Pg.41]    [Pg.121]   
See also in sourсe #XX -- [ Pg.92 ]




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