BMJ  2006;332:1133 (13 May), doi:10.1136/bmj.332.7550.1133

Research

Drug points

Sodium in soluble paracetamol may be linked to raised blood pressure

¹ Rheumatology Department, Royal Hallamshire Hospital, Sheffield S10 2JF

A 58 year old woman was diagnosed as having polymyalgia rheumatica in 2000. Her blood pressure was slightly raised (140/74 mm Hg). Her past medical history was otherwise unremarkable and her condition stable.

She takes 5 mg prednisolone a day, up to six over the counter Panadol tablets (GlaxoSmithKline, Brentwood; 500 mg paracetamol) a day, and Calcichew D3 Forte (Shire, Basingstoke; 1.25 g calcium carbonate and 10 µg colecalciferol) twice a day.

She complained of headaches, dizziness, and lethargy at a follow-up appointment in March 2004. She was hypertensive, with readings averaging 210/110 mm Hg. We advised her to see her general practitioner to recheck this.

Her blood pressure varied between 158/79 and 210/110 mm Hg over the next few days. Then she mentioned that eight weeks previously she had switched from Panadol tablets to soluble Panadol. Her lifestyle had apparently remained otherwise unchanged.

Each soluble Panadol contains 427 mg sodium. Her daily intake of sodium from six soluble tablets was 2.562 g, not including dietary sodium. The UK government recommends a daily intake of 2 g sodium (5 g salt) for women,¹ and the World Health Organization recommends limiting sodium intake.² Salt intake is linked to blood pressure.³ After returning to insoluble Panadol, her blood pressure was 145/85 mm Hg, confirmed by her general practitioner.

The increase in blood pressure seems temporally related to the switch in drug, which substantially increased in her sodium intake. This case shows the hypertensive effect that the high sodium content in a soluble paracetamol preparation may cause, particularly in susceptible patients. It also emphasises the importance of inquiring about over the counter drugs.

GlaxoSmithKline has no record of similar reports and felt it "unlikely that the sodium caused such a large increase in blood pressure," given that restricting dietary sodium in normotensive and hypertensive populations produces modest reductions in blood pressure.⁴ The UK Committee on Safety of Medicines knows of no similar cases, but its database relates primarily to paracetamol's adverse effects and not non-drug ingredients.

Competing interests: None declared.

References

1. Scientific Advisory Committee on Nutrition. Salt and health. London: Stationery Office, 2003.
2. World Health Organization. Global strategy on diet, physical activity, and health. In: Fifty seventh world health assembly. Item 12.6. WHA 57.17. Geneva: WHO, 2004. www.who.int/gb/ebwha/pdf_files/WHA57/A57_R17-en.pdf (accessed 27 Mar 2006).
3. Chobanian AV, Hill M. National Heart, Lung, and Blood Institute workshop on sodium and blood pressure: a critical review of current scientific evidence. Hypertension. 2000;35: 858-63.[Free Full Text]
4. Midgley JP, Matthew AG, Greenwood CM, Logan AG. Effect of reduced dietary sodium on blood pressure: a meta-analysis of randomized controlled trials. JAMA 1996;275: 1590-7.[Abstract/Free Full Text]

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