Scabicides (antiscabious agents) are compounds used to control the mite Sarcoptes scabiei, an organism that thrives under conditions of poor personal hygiene. The incidence of scabies is believed to be increasing in the United States and worldwide and has, in fact, reached pandemic proportions.99 Pediculicides (antipedicular agents) are used to eliminate head, body, and crab lice. Ideal scabi-cides and pediculicides must kill the adult parasites and destroy their eggs.
Benzyl benzoate is a naturally occurring ester obtained from Peru balsam and other resins. It is also prepared synthetically from benzyl alcohol and benzoyl chloride. The ester is a clear colorless liquid with a faint aromatic odor. It is insoluble in water but soluble in organic solvents.
Benzyl benzoate is an effective scabicide when applied topically. Immediate relief from itching probably results from a local anesthetic effect; however, a complete cure is frequently achieved with a single application of a 25% emulsion of benzyl benzoate in oleic acid, stabilized with triethanolamine. This preparation has the additional advantage of being essentially odorless, nonstaining, and nonirritating to the skin. It is applied topically as a lotion over the entire dampened body, except the face.
Lindane is 1,2,3,4,5,6-hexachlorocyclohexane, y-benzene hexachloride, or benzene hexachloride (Kwell, Scabene, Kwildane, G-Well). This halogenated hydrocarbon is prepared by the chlorination of benzene. A mixture of isomers is obtained in this process, five of which have been isolated: a, (, y, 8, and e. The y-isomer, present to 10% to 13% in the mixture, is responsible for the insecticidal activity. The y-isomer may be separated by various extraction and chromatographic techniques.
Lindane occurs as a light buff to tan powder with a persistent musty odor, and it is bitter. It is insoluble in water but soluble in most organic solvents. It is stable under acidic or neutral conditions but undergoes elimination reactions under alkaline conditions.
The action of lindane against insects is threefold: it is a direct contact poison, it has a fumigant effect, and it acts as a stomach poison. The effect of lindane on insects is similar to that of DDT. Its toxicity in humans is somewhat lower than that of DDT. Because of its lipid solubility properties, however, lindane when ingested tends to accumulate in the body.
Lindane is used locally as a cream, lotion, or shampoo for the treatment of scabies and pediculosis.
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