F. Other Anti-allergic Agents

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Sodium cromoglycate (IntalR) and nedocromil sodium (TiladeR) are anti-inflammatory agents used in the prophylaxis of asthma.


Neither Sodium cromoglycate (SCG) nor nedocromil sodium (NS) have direct bronchodilator or antihistamine properties, and neither is related to corticosteroids. When SCG is inhaled prior to challenge, it is capable of inhibiting both the early and late phase response to a variety of inhaled allergens, bronchoconstrictor agents such as sulphur dioxide and exercise. It was originally thought that the mode of action of SCG was by inhibition of mediator release from activated mast cells, but its ability to block the bronchoconstriction caused by irritant stimuli and exercise suggests that this is not the sole mechanism. SCG obviously modifies the release of inflammatory mediators but the exact mode of action of remains to be determined. Nedocromil sodium has been shown to inhibit the release of inflammatory mediators from a variety of inflammatory cells. Like SCG, when inhaled prior to challenge, it is capable of inhibiting the early and late phase response to inhaled allergens, bronchoconstrictor agents and exercise, and is thought to be more effective than SCG, especially in older patients.


Both drugs are taken by the inhaled route using either an aerosol or powder for SCG and in the form of an aerosol for NS. The plasma half life is approximately 90 minutes for SCG and 2 hours for NS. Since both drugs are topically active, there is no relationship between plasma levels and clinical effect. Neither drug undergoes any significant metabolism and both are excreted in urine and faeces.

Therapeutic Use

Both drugs are used in the prophylaxis of asthma. Since neither drug has direct bronchodilator properties, they have no effect on the acute symptoms of asthma and it should be stressed that they are not to be used as "rescue" therapy. When taken on a regular basis, both drugs will reduce the frequency of symptoms of asthma and may prevent asthma induced by a variety of stimuli including exercise, cold air and other inhaled irritants. SCG is taken in the dosage range 20-160mg/day and NS 8-16mg/day. Sodium cromoglycate seems to be more effective in younger patients, especially those that have a definite allergic element to their asthma. Nedocromil sodium is effective in adults and is thought to be equivalent to about 400 g/day of beclomethasone dipropionate in the control of asthma, and is a possible alternative to inhaled corticosteroids in the initial management of mild asthma or used to reduce the requirements of inhaled corticosteroids. Sodium cromoglycate is also available in a variety of preparations for the treatment of seasonal rhinitis and ocular symptoms due to hayfever.

Side effects and Overdosage

No serious side effects from SCG or NS have been recorded. Some patients may complain of an odd taste following the inhalation of NS.

Further Reading

Bone MF, Kubik MM, Keaney NP, Summers GD, Connolly CK, Sherwood Burge P, Dent RG, Allan GW. Nedocromil sodium in adults with asthma dependent on inhaled corticosteroids: a double blind, placebo controlled study. Thorax. 1989;44:654-9.

Fairfax AJ, Allbeson M. A double-blind group comparative trial of nedocromil sodium and placebo in the management of of bronchial asthma. Journal of International Medical Research. 1988;16:216-24.

Kronig P, Hordvik NL, Kreutz C. The preventive effect and duration of action of nedocromil sodium and cromolyn sodium on exercise-induced asthma (EIA) in adults. Journal of Allergy and Clinical Immunology. 1987;79:64-8.

Kuzemko JA. Twenty years of sodium cromoglycate treatment: a short review. Respiratory Medicine. 1989;83 (Suppl A):11-6. Holgate ST. Reflections on the mechanism(s) of action of sodium cromoglycate (Intal) and the role of mast cells in asthma. Respiratory Medicine. 1989;83 (Suppl A):25-31.

Thomson NC. Nedocromil Sodium: an overview. Respiratory Medicine. 1989;83:269-76. Warner JO. The place of Intal in paediatric practice. Respiratory Medicine. 1989;83 (Suppl A):33-7.

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