Since its discovery in 1960’s, Oral Rehydration Salts (ORS) solution has been used successfully in millions of cases worldwide for the treatment of dehydration due to diarrhea. From 1978 WHO recommended a single formulation ORS to treat or prevent dehydration from diarrhea of any etiology, including cholera, and in individuals of any age. It has been used successfully for more than three decades in millions of cases worldwide and contributed substantially to the reduction of mortality from diarrhea, especially in the developing nations.
In 1987, UNICEF termed ORS a medical breakthrough of the 20th Century. It said “no other medical breakthrough has had the potential to prevent so many deaths over such a short period of time and at so little cost”
Standard ORS formula: This formulation is slightly hypertonic that contains 90 mEq/liter of sodium with a total osmolarity of 311 mOsm/liter (Table1). The osmolarity of body fluids is in the vicinity of 286 ± 4 mOsm/ kg (often referred as 280 mOsm/ liter). Although the WHO-ORS is effective in the prevention of diarrhea, there has been concern that the solution, which is slightly hyperosmolar may risk hypernatremia, especially in infants. In addition, WHO-ORS does not reduce stool output or duration of diarrhea.
Reduced osmolarity ORS solution: Various studies in recent past showed that the efficacy of ORS solution for treatment of children with acute noncholera diarrhea is improved by reducing its sodium and glucose contents, and its total osmolarity to 245 mOsm/ liter. The 13th WHO Model list of essential medicines has replaced the standard ORS formulation with a new reduced osmolarity ORS (RED OSM ORS) 4. The composition of the New WHO-ORS (RED OSM ORS) is given in table 2.
Since 2003, WHO and UNICEF are recommending the use of a new ORS formulation of improved effectiveness. Although this single ORS (REDUCED OSM) formulation is recommended, WHO and UNICEF have previously published criteria, which remain unchanged, for acceptable ORS formulations. These criteria are listed below (table3); they specify the desired characteristics of the solution after it has been prepared according to the instructions on the packet.
Rational use of ORS: There are a number of brands of ORS products available in the Indian market which do not adhere to WHO specifications. Additionally, many patent and proprietary ORS products are irrational. There are many ORS products, in Indian Market, containing high glucose concentration to improve the taste and thereby the sale and the profits. The ORS products containing a high concentration of glucose not only become ineffective in a person suffering from diarrhea but also cause osmotic diarrhea and exacerbate the existing situation.
Because of the improved effectiveness of reduced osmolarity ORS solution, especially for children with acute, non-cholera diarrhoea, WHO and UNICEF now recommend that countries use and manufacture the RED OSM ORS (having osmolarity of 245 mOsm/l) formulation in place of the previously recommended ORS solution with a total osmolarity of 311 mOsm/l. This reduced osmolarity ORS may be used in place of standard ORS for treating adults with cholera, but careful monitoring is advised. The health care personnel’s (especially pharmacist’s) intervention in making a sensible decision of using reduced osmolarity and standard WHO-ORS solutions based on the information discussed is likely to promote rational use of ORS solution.