Zimelidine

Zimelidine (Normud®, Zelmid®) was the first marketed selective serotonin reuptake inhibitor (SSRI) antidepressant. It is a pyridylallylamine, structurally different from other antidepressants. The substance was developed in the early 1980s by the Swedish company Astra AB following a search for drugs with structures similar to chlorpheniramine (it is a derivative of Chlorphenamine), an antihistamine with antidepressant activity. It was then licensed to other drug producers.

Zimelidine has been banned worldwide due to serious, sometimes fatal, cases of central and/or peripheral neuropathy known as Guillain-Barré syndrome and due to a peculiar hypersensitivity reaction involving many organs including skin exanthema, flu-like symptoms, arthralgias, and sometimes eosinophilia. Additionally, zimelidine was charged to cause an increase in suicidal ideation and/or attempts among depressive patients. After its ban, it was succeeded by fluvoxamine and fluoxetine (derived from the antihistamine diphenhydramine) in that order, and the other SSRIs.

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Mechanism of action

The mode of action is a strong reuptake inhibition of serotonin from the synaptic cleft. Postsynaptic receptors are not acted upon.

Other uses

Zimelidine was reported by Montplaisir and Godbout to be very effective for cataplexy in 1986, back when this was usually controlled by tricyclic antidepressants, which often had anticholinergic effects.^[1] Zimelidine was able to improve cataplexy without causing daytime sleepiness.^[2]

Side effects

Most often reported were:

• Dry mouth, dryness of pharyngeal and nasal membranes
• Increased sweating (hyperhidrosis)
• Vertigo
• Nausea

Interactions

• MAO inhibitors - severe or life-threatening reactions possible

Dosage

The former doses were 200 to 400mg daily in outpatients and up to 600mg in inpatients.

References

• PubChem Substance Summary: Zimelidine National Center for Biotechnology Information.
• Bruce G. Charlton, Self-management of psychiatric symptoms using over-the-counter (OTC) psychopharmacology: the S-DTM therapeutic model - self-diagnosis, self-treatment, self-monitoring. Medical Hypotheses 2005; 65: 823-828.

1. ^  Caille G, Kouassi E, de Montigny C. (1986). "Pharmacokinetic study of zimelidine using a new GLC method". Clinical Pharmacokinetics 8 (6): 530-40. PMID 6228368.
2. ^  Godbout R, Montplaisir J. (1986). "The effect of zimelidine, a serotonin-reuptake blocker, on cataplexy and daytime sleepiness of narcoleptic patients.". Clinical Neuropharmacology 9 (1): 46-51. PMID 2950994.
3. ^  see Godbout et al. 1986