Amantadine and Livedo reticularis
Livedo reticularis refers to a net like pattern of reddish blue skin pigmentation (livere = blue; reticularis = net like). It sometimes occurs in patients taking amantadine and usually clears within 1 month or so. Let’s have a detailed look into the mechanism behind this effect.
Amantadine stands for ‘adamantane’ + ‘amine‘. Adamantane is an organic compound which is formed by the fusion of three cyclohexane rings. It was named so as the rings had an arrangement like a diamond crystal (Greek: adamantinos = diamond).
Mechanism of Action : Amantadine was originally an antiviral agent used against Influenza A. It was by chance found to have relatively weak anti parkinsonism properties. Amantadine exerted it’s anti parkinsonian actions through antagonizing the effects of adenosine at Adenosine A2a receptors, which inhibited D2 receptor functions and also by catecholamine release from peripheral stores.
Thus the release of physiologically active neurotransmitters from nerve terminals of sympathetic nervous system is blocked by Amantadine. Sympathetic nervous system discharge is responsible for a sustained state of partial contraction in arteries and arterioles. Dilation of capillaries and venules with relative stasis produce the cyanotic discoloration called as Livedo Reticularis. It a reversible side effect with resolution after discontinuation of the drug.
