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Long-term ergotamine abuse: effect on adrenergically induced mydriasis
M Fanciullacci1, M Alessandri, U Pietrini
1Institute of Internal Medicine and Therapeutics IV, Headache Centre, Florence University, Firenze, Italy.
Clinical Pharmacology and Therapeutics
|March 1, 1992
Summary
Long-term ergotamine use in migraine patients alters iris sympathetic transmission, causing greater pupillary dilation with tyramine eyedrops. This effect is reversible after drug withdrawal, suggesting a temporary change in sympathetic activity.
Area of Science:
- Neuroscience
- Pharmacology
- Ophthalmology
Background:
- Ergotamine is a medication used for migraine treatment.
- Long-term use of ergotamine may affect autonomic nervous system function.
- Sympathetic innervation of the iris controls pupillary size.
Purpose of the Study:
- To investigate the effect of long-term ergotamine abuse on sympathetic iris function.
- To compare the mydriatic response to different sympathomimetic eyedrops in migraine patients with and without ergotamine abuse history.
Main Methods:
- Patients with and without a history of long-term ergotamine abuse received therapeutic doses of ergotamine.
- Mydriasis was measured after instillation of phenylephrine (an alpha 1-agonist) and tyramine (a noradrenaline releaser).
- The enhanced response to tyramine was monitored after drug withdrawal.
Main Results:
- Phenylephrine-induced mydriasis was similar in both patient groups.
- Tyramine-induced pupillary dilation was significantly greater in patients with a history of ergotamine abuse.
- The enhanced tyramine response diminished after ergotamine withdrawal.
Conclusions:
- Continuous ergotamine medication leads to reversible alterations in sympathetic transmission within the iris.
- These changes in iris sympathetic function may be linked to central inhibition of pupillary sympathetic activity.