While pyridoxine (vitamin B6) is a less well-known vitamin compared to cyanocobalamin (vitamin B12), there are some potential consequences from deficiency. I am going to layout pyridoxine clinical pearls including some common medications that may cause deficiency and additional situations where pyridoxine may be used.
Isoniazid is an agent used for the treatment of tuberculosis and it is well known to cause (pyridoxine) vitamin B6 deficiency. A possible consequence of isoniazid use is neurologic side effects like neuropathy. Isoniazid interferes with the action of vitamin B6 in neurons which can lead to this complication. Because of this, we will supplement patients with pyridoxine to help reduce the incidence of this adverse effect. This is a classic pharmacology nugget that may show up during finals and board exams.
Hydralazine (used for hypertension) and pyrazinamide (used for tuberculosis) are also agents that may contribute to the risk of pyridoxine deficiency.
From a medical standpoint, there are some situations where the risk for pyridoxine deficiency may be increased. Patients who are malnourished, or who have a history of excessive drinking are at higher risk for low pyridoxine levels. Geriatric patients may be at higher risk for deficiency as well. Autoimmune conditions like rheumatoid arthritis may increase the risk for deficiency as well as GI conditions like Celiac disease and Crohn’s.
In addition to the prevention of pyridoxine deficiency in patients taking tuberculosis agents, the most common use I have seen in clinical practice is pregnancy-induced nausea and vomiting. It is generally considered safe in pregnancy and you may see it used in combination with doxylamine. This is also a question I have seen come up on pharmacology exams in the past!
These are my most important pyridoxine clinical pearls. Have you seen pyridoxine used in any other situations?
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While pyridoxine is FDA approved as a first line treatment for nausea and vomiting in pregnancy, it is also used first line for Hyperemesis Gravidarum (HG). Since these women cannot keep pills down, I recommend looking for drops or dissolving tablets if OTC. Note the dosing is different for OTC, Diclegis and Bonjesta, and HG patients have reported the best effect from Bonjesta. @HGPharmacist
Wonderful information.