Pyridoxine hydrochloride

How it works

It is converted to pyridoxal phosphate, a coenzyme for amino acid metabolism and an early step in haem synthesis (delta-aminolaevulinic acid formation), which can improve haemoglobinisation in responsive sideroblastic anaemia.

Prescribing in practice

• Prolonged use of high doses can cause a peripheral sensory neuropathy, so avoid unnecessarily high or long-term dosing.
• Only a subset of sideroblastic anaemias are pyridoxine-responsive, so review the haematological response and stop if there is no benefit.
• It can reduce the efficacy of levodopa given without a dopa-decarboxylase inhibitor, so check concurrent therapy.

Monitoring

Monitor the full blood count and haemoglobin response in sideroblastic anaemia, and review for any sensory neuropathy with prolonged use.

Counselling the patient

• Take as directed and do not exceed the recommended amount because excess can affect the nerves.
• Report any numbness, tingling or unsteadiness in the hands or feet.
• Continued treatment depends on whether the blood count improves.

Evidence & guidelines

Pyridoxine is the recognised treatment for pyridoxine-responsive sideroblastic anaemia and for preventing isoniazid-induced deficiency.