Phenobarbitone tablets

A comparison of dissolution properties from matrix tablets prepared from microcapsules and mixtures containing phenobarbitone and poly(DL-lactic acid)... 

The release of the drug phenobarbitone (PB) from tablets prepared using simple mixtures of DL-PLA and PB, as well as from the corresponding tablets from microencapsulated PB, is reported. These results are compared with release from the original microcapsules. 

Table 2—Amount of drug released from phenobarbitone-poly (DL-lactic acid) tablets...

Fig. 5— Higuchi plot of the release of phenobarbitone from phenobarbitone-DL-PLA tablets. Systems and ratios microeapsules 1 1 2 1 matrices 1 1 2 1 compressive forces (a) 2 kN, (b) 5 kN and (c) 10 kN. Dissolution conditions Buffer pH2 stirring rate, 100 rev min-1 t=37°C.

El-Yazbi et al. reported an application of a derivative-differential ultraviolet spectrophotometric method for the determination of oxazepam or phenobarbitone in the presence of dipyridamole [24]. Tablets containing the drugs were powdered and dissolved in ethanol. For solutions of oxazepam and dipyridamole, two portions of each were diluted with 0.1 N sulfuric acid and 0.05 M sodium borate, and subjected to differential spectrophotometry with measurements being made at 283, 292, 298 and 282, and 307, and 296 nm. First derivative (ADi)... 

Barbiturates and benzodiazepines are usually encountered by the forensic scientist as tablet or capsule preparations that have been diverted from licit somces, or, particularly in the case of barbiturates, as cutting agents in other drug materials (for example, phenobarbitone in heroin samples). 

Malamataris, S. Dimitriou, A. Moisture sorption profiles and tensile strength of tableted phenobarbitone formulations. J. Pharm. Pharmacol. 1990, 42, 158-163. 

Certain food and drug regulations regard all slow-release preparations as drugs and require their safety to be established prior to clinical application. Thus, a potassium ion-selective electrode has been employed to follow [416] the release parameters of 12 encapsulated potassium chloride tablets. Several of the tablets showed only medium dissolution rates for potassium and are unlikely to cause adverse effects such as gut ulceration. A sodium electrode has been similarly used to study the release of sodium phenobarbitone through a dialysis membrane into tris buffer [417]. Sodium in organic compounds has also been determined with an Orion 94-11 sodium electrode following combustion in a closed flask [418]. 

Table IX. Recovery of Phenobarbitone From Commercial Tablets...

Phenobarbitone is often compounded with other drugs such as stil-boestrol, theobromine and aminophylline in tablet formulations. A simple infra-red method of assay has been found useful on such materials." The samples are made up in chloroform solution and the carbonyl stretching absorption band at 1,740 cm" is utilised. 

Capsules of Amylobarbitone Sodium, J5.P., Tablets of Amylobar-bitone Sodium, P.P. Tablets of Barbitone Sodium, P.P., Tablets of Pentobarbitone Sodium, P.P., and Tablets of Phenobarbitone Sodium, P.P. The tablets are liable to absorb carbon dioxide rapidly on exposure and liberate a considerable proportion of free barbiturate, extractable with ether from the powdered material. 

Bodin has applied direct argentimetric potentiometric titration to phenobarbitone and its sodium salt in preparations containing a variety of standard diluents. He eliminates uncertainty in the end-point potential by determining the potential of a standard blank solution (saturated with silver carbonate) for each sample just prior to titration and using this as the end-point potential for titration of the sample. Stearates, halides and ammonium salts interfere and special consideration must be given to samples containing polyethylene glycols, alcohol, or hexamine. He includes a procedure for removal of stearates from tablets. 

For tablets and capsules (stearates present). Weigh an amount of sample equivalent to about 500 mg of phenobarbitone and transfer to a 250-ml graduated flask with exactly 25 ml of 95 per cent ethanol. Add 25 ml of water and swirl the flask until the undissolved solid is evenly dispersed. Add 125 ml of a 3 per cent solution of anhydrous sodium carbonate, shake and dilute to volume with water. Filter, preferably with suction, through a fine, retentive filter paper, rejecting the first 25 ml of the filtrate and collecting the remainder in a dry receiver. Titrate 100-ml portions of the filtrate with 0-1N silver nitrate to the standard blank potential. Correct for the blank as before. 

Tablets of Belladonna and Pbenobarbitone, B.P.C. Each tablet contains approximately 49 mg of phenobarbitone and 26 mg of dry extract of belladonna. The B.P.C, assay for phenobarbitone is as follows ...

Weigh an amount of powdered tablets equivalent to about 0 13 g of phenobarbitone, dissolve in 10 ml of 0 1 N sodium hydroxide and saturate the solution with sodium chloride. Make acid to litmus paper with concentrated hydrochloric acid and extract with 15-ml quantities of ether until extraction is complete. Extract the combined extracts with four 20-ml quantities of a mixture of 6 ml of 20 per cent sodium hydroxide solution and 76 ml of brine, combine the aqueous extracts and make acid to litmus paper with concentrated hydrochloric acid. Extract with 15-ml quantities of ether until extraction is complete, combine the ether extracts and wash with two 2-ml quantities of water, rejecting the washings. Filter the ether solution, wash the filter with ether, evaporate the ether from the combined extracts and washings and dry the residue of phenobarbitone to constant weight at 105°. 

Tablets of Phenobarbitone and Theobromine, B.P.C. Contain 5 grains of theobromine and J grain of phenobarbitone.

To a weight of powder equivalent to three tablets add 20 ml of ethanol, shake to dissolve the phenobarbitone, filter through a Gooch crucible, wash the precipitate twice with 20 ml portions of ethanol followed by 10 ml of water. Dry at 105° and weigh the theobromine. Evaporate the filtration washings, dissolve the residue in dilute sodium hydroxide and transfer to a separator, acidify and extract the phenobarbitone with ether. Evaporate, dry and weigh. 

When ergotamine is to be determined in tablets containing other drugs (e.g. caffeine, phenacetin and phenobarbitone) the colorimetric method cannot be applied directly. Alexander has described a column-chromato-graphic method of separation consisting of preliminary separation of the alkaloids from water-soluble excipients by means of a sodium bicarbonate column followed by retention of the ergotamine on a strongly acidic citric acid column from which the caffeine, phenacetin and phenobarbitone are... 

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