Due to its very narrow therapeutic index, Theophylline is known to cause a wide variety of side-effects and even toxicity.

Also, portfolios heavy in certain areas - pharmaceuticals, say, or Japanese or cyclical stocks - should be hedged with puts from those narrow indexes.

Medication is said to have a narrow or wide therapeutic index.

However this use has been limited due to their narrow therapeutic index, and the development of more-advanced medicines for these conditions.

Its clinical use has been limited by its narrow therapeutic index and high inter- and intra-individual pharmacokinetic variability.

Tobramycin is thus said to be a drug with a narrow therapeutic index.

"Closing all markets based on an arbitrary move in a narrow index is likely to be counterproductive and disruptive," the report said.

The occurrence of adverse drug reactions is common, owing to its narrow therapeutic index (the margin between effectiveness and toxicity).

The bulb-like corms of Colchicum autumnale contain colchicine, a useful drug with a narrow therapeutic index.

Patients treated often suffered side effects due to the narrow therapeutic index of these products.