Benzocaine Solution

Mill and screen the menthol and benzocaine to reduce the product particle size. 

Add the menthol, benzocaine, sodium saccharin, and monoammonium glycerizzinate into a clean vessel. 

Add eucalyptus oil and ethanol to the vessel. Subsequently add the poloxamer and water to 

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Antipyrine Bulk HPLC Silica CH2Cl2-MeOH (1% NH4OH) (98 2) 254 nm GC [9] ear drops [153,154] USP 23, ordinary impurities, p. 142, with benzocaine solution. with phenylephrine, assay by HPLC, p. 125 [5] [9]... 

Read the number of milligrams of benzocaine equivalent to the observed extinction of the test solution from a calibration graph prepared by treating amounts of standard benzocaine solution covering the range 80 to 120 jug in the same way. (Standard benzocaine solution contains 10 mg per litre in 0 1 N hydrochloric acid.)... 

Higuchi and Lachman [122] pioneered the approach of improving drug stability by complexation. They showed that aromatic esters can be stabilized in aqueous solutions in the presence of xanthines such as caffeine. Thus, the half-lives of benzocaine, procaine hydrochloride, and tetracaine are increased by approximately two- to fivefold in the presence of 2.5% caffeine. This increase in stability is attributed to the formation of a less reactive complex between caffeine and the aromatic ester. Professor K. A. Connors has written a comprehensive textbook that describes methods for the measurement of binding constants for complex formation in solution—along with discussions of pertinent thermodynamics, modeling statistics,... 

Benzocaine Dissolve 0.2 g in 5 ml alcohol, previously acidified with a few drops of dil. HN03 and add a few drops of AgN03 solution. No turbidity is produced immediately. 

Tyrothricin (0.5 mg/kg skin cream, 0.2 mg/ml solution (topical), 0.05% as otic solution with benzocaine... 

Besides using a simple mobile phase requiring little or no method development, the sample preparation steps can be simplified. This has been shown in the analysis of benzocaine ointment which is dissolved in tetrahy-drofuran, filtered, and injected (Figure 5.11). Using an identical approach, a solution of the corticosteroid halcinonide is resolved from the excipi-... 

Disposition in the Body. Benzocaine is metabolised by hydrolysis to 4-aminobenzoic acid. At the concentrations normally used (2 to 10%) it is comparatively non-irritant and non-toxic, having only about one-tenth the toxicity of cocaine. The maximum safe amount for topical use is 5000 mg (25 ml of a 20% w/v solution). 

Alternatively, Rubino and Yalkowsky found that a was a linear function of cosolvent polarity for a given solute. This is illustrated in Fig. 3 for the three lipophilic compounds phenytoin, diazepam, and benzocaine. Thus, knowledge of the solubility of a given drug in water and at least two cosolvents would permit cr to be estimated for other cosolvents by interpolation using an index of the desired cosolvent polarity. These studies permit the use of Eq. (4) as a means to rationally choose or eliminate solvents for formulation studies based on limited experimental solubility data and commonly obtained indexes of solute and solvent polarity. 

Fig. 3 Relationship between slope a and solvent polarity, represented by the solvent interfacial tension, for three solutes. A = phenytoin B = diazepam C = benzocaine. (From Ref l)...

Auralgan Otic solution Benzocaine Antipyrine Glycerin... 

In aqueous alcoholic solutions, it very readily solubilizes essential oils. Aqueous solutions of hydrophobic drugs (e.g. miconazole, hexetidine, clotrimazole, benzocaine) can also be prepared with Cremophor EL. Cremophor EL has also been used as a solubilizing agent for drugs like cyclosporin A, paclitaxel, and cisplatin. Cremophor LLP is manufactured by purifying Cremophor EL and is therefore suitable for parenteral applications, e.g. Taxol preparations. In oral formulations, the taste of polyoxyl 35 castor oil (Cremophor EL) can be masked by a banana flavor. 

Figure 6.19 pH profile for the sorption of benzocaine by nylon 6 powder from buffered solutions at 30°C and ionic strength 0.5 mol dm" (O) and the corresponding drug dissociation curve ( ). 

Einhom s clinical success with the poorly walcr soluble Oithoforms resulted in the introduction of ethyl 4-aminoben-zoate into clinical use in 1902 under the name Anesthesinc. It was later given the approved name of benzocaine. Ritsert had noticed in 1890 that this water-insoluble compound had numbed his tongue and so to improve its water solubility, it had been formulated as the hydrochloride. As aromatic amines are weak bases, however, the resulting solution had proved too acidic, and he had discounted its clinical use. 

In a collaborative study on the quantitative determination of cocaine hydrochloride in powders and tablets that also contain other drugs (i.a. caffeine, procaine hydrochloride and benzocaine) as well as lactose, mannitol and starch, the free cocaine base was extracted with chloroform from an aqueous solution after addition of KjHPO. Tetracosane was added... 

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