POULTICE

Definition: Poultice are paste-like preparations used externally to reduce inflammation because they retain heat well. After heating, the preparation is spread thickly on a dressing and applied, as hot as the patient can bear it, to the affected area.

Uses;

(i)     Glycerol, because of its hygroscopic nature, is believed to draw infected materials from the tissues when the poultice is used for boils and similar infections.

(ii)         Methyl salicylate (an antirheumatic drug),

            thymol (a powerful bactericide),

            boric acid (a weak antimicrobial agent),

            and peppermint oil (which contributes to the smell) are used for different purposes.

Method of applying the poultice:

(i)     Fro use, the poultice is heated, with occasional  stirring, until it can only be  tolerated on the back of the hand.

(ii)   Then it is spread thickly on lint or other dressing  and applied to the affected area which is sometimes first covered with muslin to facilitate removal after use.

(iii) A thick layer of cotton wool is applied to retain the heat and a covering of oiled silk may be added to protect clothing.

Example:

The only example given in the pharmacopoeia is Kaolin Poultice B.P.C.

Formula:                     Heavy kaolin, finely sifted and dried at 100⁰C                        52.7 g

                                    Boric acid, finely sifted                                                           4.5 g

                                    Methyl salicylate                                                          0.2 ml

                                    Thymol                                                                                    50 mg

                                    Peppermint oil                                                             0.05 ml

                                    Glycerin                                                                       42.5 g

Procedure:

(a)    Kaolin is spread in a suitable quantity of kaolin in a thin layer, e.g.  on a tray of aluminium foil, and dried at 100⁰C until the weight is constant. Allowed to cool down and then passed through No. 180 sieve.

(b)   Boric acid and kaolin are mixed in a mortar. Gradually the mixed powder is triturated with glycerol to form a smooth paste.

(c)    The paste is transferred to a heat-resistant glass-jar, protected either wit a paper or aluminium foil and heated at 120⁰C for 1 hour in a hot-air oven, with occasional stirring. The antimicrobial effects of the heat and glycerol destroy the sporing pathogens that may be in the kaolin. (Above 1200C glycerin may degrade).

(d)   After cooling a mixture of thymol, methyl salicylate and peppermint oil are mixed. (Eutectic mixture).

(e)    Kaolin poultice is stored in well closed containers to prevent loss of volatile ingredients and absorption of moisture from the atmosphere by glycerin.