Potassium chloride 10% solution ↔ mEq

Convert between the volume of potassium chloride 10% oral solution and the milliequivalents of potassium it supplies, and find the equivalent number of tablets.

High-consequence calculationPotassium chloride is a high-alert medication. Concentrated potassium has caused fatal errors; verify the concentration, the total dose, and the route independently.

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What is this for?

Potassium chloride 10% oral solution supplies 20 mEq per 15 mL. Because orders are written in milliequivalents while the solution is measured in millilitres, this conversion is needed at almost every dispensing of the liquid formulation.

How to use it

Choose whether you are converting a volume to milliequivalents or the reverse.
Enter the amount.
Select a tablet strength if you want to know how the liquid dose compares to solid dosage forms.

Worked example

A patient is prescribed 30 mL of potassium chloride 10% oral solution. How many milliequivalents is that?

Answer: 30 mL × (20 mEq ÷ 15 mL) = 40 mEq, equivalent to two 20 mEq tablets.

Clinical pearls & pitfalls

The labelled 20 mEq per 15 mL is a rounded value. Working it out stoichiometrically from the 10% w/v strength gives a marginally higher figure — use the label.
Potassium chloride is on the ISMP high-alert list. Concentrated potassium chloride vials are removed from ward stock in most institutions precisely because of fatal administration errors.
Oral potassium is generally preferred where the patient can take it and the deficit is not severe. It is safer than the intravenous route and, for a given dose, no less effective.
Correct magnesium alongside potassium. Hypokalaemia is refractory to replacement while hypomagnesaemia persists, because magnesium depletion drives renal potassium wasting.
Different potassium salts are not interchangeable for every indication. Chloride is the salt of choice in hypokalaemic metabolic alkalosis; acetate, citrate, or bicarbonate are used where an alkalinising effect is wanted.

Assumptions & limitations

Specific to the 10% w/v oral solution supplying 20 mEq per 15 mL. Other concentrations exist — always check the product in hand.
Does not calculate a replacement dose or a rate. Potassium replacement must be individualised to the deficit, renal function, and the clinical urgency.
Does not address intravenous potassium, where concentration limits and infusion rates are governed by institutional protocol.

References

Institute for Safe Medication Practices. ISMP List of High-Alert Medications in Acute Care Settings. link
Product labelling for potassium chloride oral solution USP 10%.
Cohn JN, Kowey PR, Whelton PK, Prisant LM. New guidelines for potassium replacement in clinical practice. Arch Intern Med. 2000;160(16):2429-2436.