Patiromer on the Pharmaceutical Benefits Scheme

Patiromer is now available on the Pharmaceutical Benefits Scheme (PBS) for the treatment of chronic hyperkalaemia. Criteria to qualify for PBS-subsidised treatment include:

• Stage 3-4 chronic kidney disease;
• Condition not adequately controlled by a low potassium diet;
• At least two episodes of hyperkalaemia (serum potassium ≥ 6.0 mmol/L) within the 12 months before initiating patiromer; and
• Patient must be receiving a renin-angiotensin-aldosterone system inhibitor (unless unable to tolerate).

Patiromer is a non-absorbable polymer that binds potassium in the lumen of the gastrointestinal tract. This increases the faecal excretion of potassium, thereby lowering serum levels. Patiromer is not recommended as the sole treatment of hyperkalaemia in patients with ECG changes, as the onset of effect is around four to seven hours.

Patiromer may bind some co-administered oral drugs, which could reduce their absorption. The product information lists medications that are not affected by this interaction. It is recommended that the administration of all other oral medications be separated from patiromer by at least three hours. As patiromer is not absorbed, drug interactions are expected to be confined to the gastrointestinal tract.

The incidence of adverse events was similar for patiromer and placebo groups in clinical trials. Caution is required in patients at risk of hypercalcaemia as patiromer contains calcium as part of the counterion complex, which is partially released. Magnesium levels should be monitored for at least one month after starting therapy as reductions in serum magnesium may occur.

Polystyrene sulfonate resins are another option to increase faecal potassium excretion. However, there is a lack of randomised data to support their use in the treatment of chronic hyperkalaemia, and they are also associated with serious gastrointestinal adverse effects. These factors, combined with the poor palatability of polystyrene sulfonate resins, may make patiromer a more attractive option in some cases.