Miscellaneous inorganic pharmaceutical agents

Dr. Taj Khan Dept. of Pharmaceutical Chemistry, Oriental college of pharmacy Sanpada, New Mumbai.

Expectorants

Expectorants are the drugs used orally to stimulate flow of respiratory tract secretions.By using this ciliary motion could throw mucus towards pharynx easily. Used in respiratory disorders in which secretions are purulent, viscid /excess.2 categories:1)Directly acting on bronchial secretory cells e.g. Terpin hydrate2)Reflex acting (Irritate gastric mucosa & then stimulate RT secretion e.g. NH4Cl, KI, HI syrup, Iodinated glycerine

Terpen Hydrate

Terpin hydrate is an expectorant, commonly used to loosen mucus in patients presenting with acute or chronic bronchitis, and related conditions. It is derived from sources such as oil of turpentine, oregano, thyme and eucalyptus. Though it was quite popular in the USA since the late nineteenth century, it was banned by the U.S.FDA in the 1990s due to lack of proof of efficacy.

Ammonium Chloride I.P.NH4Cl Mol wt 53.49

Also known as Ammonium muriatePreparation: By neutralization rxn, evaporation to dryness. Purification by recrystallization/ sublimation

Properties: Colourless crystals/crystalline powder, cool saline taste. Hygroscopic.Freely soluble in water & in glycerin. Sparingly soluble in alcohol.Assay: Weighed qty dissolved in water & HCHO solution is added. Titrated with 0.1N NaOH using phenolphthalein as indicatorEach mi of 0.1N NaOH = 0.005349 gm of NH4ClDose: 4-12 gm daily orally

NH3 + HCl NH4Cl

Potassium Iodide I.P.

NH4Cl Mol wt 165.87NLT 99% & NMT 100% on dried basisKI soln NF contain 10% KI with 0.05% Na2S2O3 to reduce free I2 which can form on storage

Assay: Iiodometry, weighed compound dissolved in water, HCl, CHCl3 added & Titrated with 0.05M Potassium iodate, until purple/grey color of CHCl3 layer I2 disappear Dose: 300 mg QID orally

2 Na2S2O3 I2 Na2S4O6 + 2NaI+

Emetics

Definition: Agents induce emesis/vomiting.In low dose added in anti-cough preparations.The use of emetics is limited to the treatment of poisoning with certain toxins that have been swallowed.

The act of emesis is controlled by the vomiting centre in the medulla and close to it is other visceral centres in the medulla oblongata.

Mild emetic response can stimulate respiratory tract secretion. It also minimise nausea caused by opiates e.g. Antimony K tartrate

Antimony K tartrate (Tartar emetics potassium antimonyl tartrate, potassium antimontarterate,)

K2Sb2(C4H2O6)2Double salt of potassium and antimony of tartaric acid.Preparation: Antimony potassium tartrate can be prepared by refluxing a solution of potassium hydrogen tartrate and antimony trioxide for 15 mins. The hot mixture is then filtered and crystals of Antimony potassium tartrate precipitates out as a colourless crystals

Use: Formerly used as emetics & expectorant. Now a days used for the treatment of schistosomiasis & leishmaniasis.Emetic action is slow onset followed by marked depression so not used in current clinical practice.Dose: 40 mg can be increased to 140 mg daily.