Thiamine (IV/IM — Pabrinex)

How it works

It supplies thiamine and other B-group vitamins that are essential cofactors for carbohydrate metabolism, replenishing stores rapidly enough to prevent the neurological damage of acute deficiency.

Prescribing in practice

• Anaphylaxis is the critical risk — give the IV preparation slowly and only where facilities to treat anaphylaxis are immediately available.
• Administer thiamine before or with any intravenous glucose in at-risk patients, as a glucose load can precipitate Wernicke's encephalopathy.
• Maintain a low threshold for treatment in alcohol dependence, malnutrition or persistent vomiting, where deficiency is easily missed.

Monitoring

Observe the patient during and after infusion for allergic reactions and monitor for resolution of neurological features.

Counselling the patient

• Explain this is a vitamin replacement given by drip or injection to protect the brain and nerves.
• Tell staff at once if you feel itchy, wheezy, light-headed or unwell during the infusion.

Evidence & guidelines

Parenteral thiamine for Wernicke's encephalopathy is supported by national guidance and longstanding clinical experience rather than large randomised trials.