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

Hector Warnes’ reply to Gordon Johnson

       I am grateful for your perspicacious comments. At the time the patient experienced severe tremors I checked the blood lithium levels and they were in the range of 0.6 Meq. He was taking only one tablet of Lithium XR - 450mg a day. I decreased the dose to lithium 300 mg a day but the tremor continued. There was a clear improvement after one week on Pyridoxine 100 mg a day. As soon as the tremors subsided, I increased the dose of lithium to 300 mg every 12 hours. The next lithemia showed a blood level of 1.4 Meq. I kept him on Mirtazapine 30mg hs. During that week he started to show marked improvement and after three months of optimal stability he started to swing in a hypomanic state. He had no tremors due to concomitant prescription of Pyridoxine 100 mg a day. However, since I was giving him Mirtazapine I had to reduce the dose to half a tablet of 30 mg.

       He became more stable and the hypomanic phase improved. The lithemia was in the range 1.01 Meq. The patient had no tremors this time because he was protected with Pyridoxine. However, searching the patient's past and judging from current behavior I considered that the patient had a bipolar disorder with rapid cycles. Apparently, rapid-cycle bipolarity is in the range of 40% of the bipolar disorders. You are right in considering drug interaction but also you are right about the specificity of the pyridoxine effect. To answer your queries, I would draw your attention to the references below.

       Another compounding factor would be the use of anti-depressants which are known to either trigger manic states or induce rapid cycling. I am seeing the patient every week and currently he is mildly depressed but satisfied with his status. On higher doses of lithium and Mirtazapine he reached a level of hypomania and the family got worried he would lose his judgement. His blood pressure is under control. He is intellectually very bright, has a good memory and continues to write his academic papers. He noticed that he has a loss of appetite and energy but shows no psychomotor retardation. I am requesting lithium levels every two weeks and trying to keep the therapeutic window between 0.8 and 1.2 Meq.

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(2):267-9. 

Miodownik C, Witztum E, Lerner V. Lithium-induced tremor treated with vitamin B6: a preliminary case series. Int J Psychiatry Med, 2002;32(1):103-8. 

Patten SP. Propanolol and depression: evidence from the antihypertensive trials. Can J Psychiatry, 1990;35(3):257-59. 

Xiong GL, Gagliardi JP, Jiang W. Beta-blockers and depression. Amer Journal of Psychiatry, 2010;167(2):219.

February 25, 2021