|Chapter 3: Rationality of Drugs|
4) Cough Suppresants, Expectorants and Mucolytics
Combinations containing so-called expectorants like iodides, chlorides, bicarbonates, acetates, squill, guiaphenesin, creosotes and volatile oils in addition to central cough suppressants, antihistaminics, bronchodilators and mucolytics.
Brand Name Examples: Alex cough formula (Lyka) liquid; Asthalin expectorant (Cipla) syrup; Benadryl cough formula (Parke-Davis) syrup; Bro-Zedex (Wockhardt) syrup; Clistin-DMR (Ethnor) liquid; Contac-CC (Smith-Kline Beecham) tab; Coscopin-Linctus (Biological-E) syrup; Detigen linctus (Bayer) liquid; Dilosyn expectorant (Allenburys) liquid; Dristan Expectorant (Manners) liquid; Piriton expectorant (Glaxo) liquid; Polaramine expectorant (Fulford) syrup; Zeet expectorant (Alembic) syrup; and many such others.
Comments:(i) Cough is a protective reflex of body, often a symptom of many common and self-resolving conditions like common cold.
(ii) Cough could be productive or unproductive. When unproductive and discomforting to patients, it could be suppressed by centrally acting antitussives like codeine, noscapine, or dextromethorphan.
(iii) When cough is due to allergic reasons, it can be tackled by giving H1 antagonists; when due to bronchospasm, it can be relieved by giving bronchodilators like salbutamol or terbutaline.
(iv) When the cough is productive, it should be encouraged for the purpose of expectoration. Expectorants like iodides, chlorides, guiaphenesin, creosotes, volatile oils, etc., are claimed to have expectorant value but may have no more than placebo value (Laurence, p.506). Expectorants given in effective doses are often not tolerated and produce ADR. Water inhalation as an aerosol, though cheap,is not to be despised. Simply hydrating a dehydrated patient can have a beneficial effect in lowering sputum viscosity (Laurence, p.505).
(v) Most expectorants are of unproven value as per standard Indian textbooks like Pharmacology and Pharmacotherapeutics (Satoskar, 1995, pp.308-309) and Textbook of Pharmacology (K.D.Tripathy, 3rd Edition, 1994).
(vi) The Model List of Drugs (Seventh List, WHO, 1992) has not mentioned any substance except centrally acting cough suppressants in the category of drugs for cough.
(vii) Water in the vapour form is the best expectorant according to Harrison's Textbook of Medicine.
(viii) Using expectorants is a costlier way of helping a condition which is often self-resolving.
Recommendations: (i) Preparations containing only centrally acting cough suppressants as single ingredient should be made available.
(ii) Bronchodilators may be allowed to combine with mucolytics but nothing else.
(iii) Single ingredient preparations of antihistamines may be permitted for allergic cough.
(iv) There is no need for any expectorants in present day therapeutics. Ban all preparations of expectorants.
5) Oral Enzymes and Digestives
a) Oral Enzymes for proteolytic and anti-inflammatory action, i.e., trypsin, chymotrypsin, serrati peptidase, etc.
Name Examples: Alfapsin (Lyka) tabs; Chymoral Forte (Elder) and Chymoral
Forte D.S. (Elder) tabs; Restochyme (Walter- Bushnell) tabs; Bidanzen
Forte (Biddle-Sawyer) tabs; Kineto (Systopic) tabs; Seraini (AFD) tabs
and several such others.
(iii) No pharmocokinetic and bio-equivalence studies of these preparations are available.
(iv) These enzyme preparations are not mentioned in standard textbooks of medicine.
(v) Being of animal origin they may produce allergic effects.
(vi) They are too expensive, especially for non-indications.
Recommendations: All these products must be banned forthwith.
Oral Digestive Enzyme Preparations of Pancreatin, Diastase and Taka diastase,
Brand Name Examples: Aristozyme (Aristo) caps, drops, liquid; Bestozyme (Biological-Evans) caps, syp, paediatric syrup; Digiplex (Rallis), all preparations; Essentiale (Rhone-Poulenc) caps; Festal (Hoechst) tabs; Merizyme (Mercury) syrup; Neopeptine (Raptakos) caps. drops, syrup; Paptazyme (AFD) tabs; Takazyme (Parke-Davis) powder; Unienzyme (Unichem) tabs, drops; Vitazyme (East India) liquid, drops; Vizylac (Unichem) caps, dry syrups; and several such others.
Comments: (i) Digestants are drugs that supposedly promote the process of digestion in the gastrointestinal tract in conditions characterised by a lack of one or more of the specific substances that function in the digestion of food. Although a number of products are marketed including many bizarre mixtures of components, the only preparations that merit consideration are those of pancreatic enzymes.
(ii) These preparations are employed for the treatment of conditions in which the secretion of pancreatic juice is deficient, for instance, pancreatis and mucoviscidosis (Goodman-Gillman, 1990, p.929)
(iii) Acid and peptic activity in the stomach can destroy the pancreatic enzymes. Enteric coating may prevent delivery of enzymes in the duodenum (Goodman-Gillman, 1990, p.929).
(iv) Only one tenth of the normal pancreatic output is sufficient to prevent excess fat or nitrogen loss. They are preparations of animal origin and of variable potency. Many of these drugs have been tested for specific effect in acute pancreatis and none has shown convincing benefit (Laurence, 1992, p.546)
(v) Many of the ingredients present in the above cited formulations in India, are not mentioned in standard textbooks of medicine and pharmacology.