Hector Warnes: Pyridoxine in the treatment of lithium-induced tremor 

Janusz K. Rybakowski’s comment

        I read with great interest Hector Warnes’ case report pointing to a favorable effect of pyridoxine in lithium-induced tremor. His results confirm the data of other researchers (Miodownik, Witzum and Lerner 2002; Dias Alves, Varin, et al. 2017) on the possibility of using high doses of pyridoxine in this condition.

        Certainly, a fine tremor of the upper limbs is the most frequent neurological effect of lithium. The tremor may occur as postural tremor or during any type of active movement (action tremor). It looks like an exaggeration of physiological tremor with a similar frequency range between 8 and 13 Hz, differing from resting Parkinsonian tremor which has a frequency of 4 to 6 Hz. The incidence rate of the tremor which may occur as early as several days after beginning treatment is about 20% of lithium-treated patients. Since the first reports nearly 50 years ago (Kirk, Baastrup and Schou 1973), propranolol at 30-80 mg/day has been successfully used in the treatment of lithium-induced tremor.

        In my clinical practice, the first step when a patient presents with lithium-induced tremor is a reduction of lithium dose by 1/3-1/4. In a half of such cases, the tremor disappears. However, when after decreasing the lithium dose, the tremor is still clinically relevant and interferes with the patient’s daily activities, I use propranolol, starting with 20 mg/day. In such patients, I have never observed any indication of new or worsening of existing depressive symptoms. However, the observation by Hector makes it possible in such cases to use pyridoxine as an additional therapeutic option.

References:

Dias Alves M, Varin L, Fiori LM, Etain B, Azorin J-M, Belzeaux R. Efficacy of vitamin B6 in lithium-associated tremor: A case series. J Clin Psychopharmacol, 2017;37:267-9. 

Kirk L, Baastrup PC, Schou M. Propranolol treatment of lithium-induced tremor. Lancet, 1973;7837:1086-7.

Miodownik C, Witztum E, Lerner V. Lithium-induced tremor treated with vitamin B6: a preliminary case series. Int J. Psychiatry Med, 2002;32:103-8.

October 22, 2020