Why the Australian IV fluids shortage means saline and Hartmann’s solution cannot simply be swapped

Last week, Australia’s Therapeutic Goods Administration placed intravenous (IV) fluids on its expanding register of medicines experiencing shortages. Demand has exceeded forecasts, while manufacturing problems have also constrained supply.

The shortage concerns two specific IV fluids: saline and compound sodium lactate, which is also known as Hartmann’s solution. Both are salt-based fluids.

Although some IV fluids contain different ingredients, including sugar rather than salts, patients are not simply being moved on to these alternatives. Instead, the government has opted to authorise salt-based products supplied by other overseas brands.

Why, then, do IV fluids use different chemical ingredients? And why are they not always interchangeable when supplies become limited?

We can't just inject water into a vein

Medicines administered into a vein are always delivered in a water-based solution. Pure water cannot be used, however, as additional chemicals must be included because of a scientific process known as osmosis.

Osmosis is the rapid movement of water into and out of cells in the bloodstream as the concentration of chemicals dissolved in blood plasma changes. These chemicals include salts, sugars, nutrients, medicines and proteins.

When the bloodstream contains too great a concentration of chemicals and proteins, it enters a "hypertonic" state, causing blood cells to contract. Conversely, too few chemicals and proteins make blood cells swell. The correct balance is described as "isotonic".

Combining a medicine with the appropriate quantity of chemicals for an injection or infusion keeps the concentration in the syringe or IV bag close to isotonic.

What are the different types of IV fluids?

A variety of IV fluids can be used to administer medicines. The two most commonly used are:

• 0.9% saline, an isotonic table-salt solution. It is one of the IV fluids currently in short supply.
• a 5% glucose/dextrose sugar solution. This fluid is not currently in short supply.

IV fluids are also available that combine saline with glucose, as well as fluids containing other salts:

• Ringer’s solution is an IV fluid containing sodium, potassium and calcium salts.
• Plasma-Lyte includes several sodium salts as well as magnesium.
• Hartmann’s solution (compound sodium lactate) contains several different salts. It is typically used to treat metabolic acidosis, a condition in which patients have excess acid in their bloodstream. It is in short supply.

What if you use the wrong solution?

Certain medicines remain stable only in particular IV fluids – for example, exclusively in salt-based IV fluids or exclusively in glucose.

If a medicine is mixed into an unsuitable IV fluid, it may "crash out" of the solution, meaning the patient does not receive the complete dose.

The medicine may instead break down. As well as becoming ineffective, it could produce serious side effects.

Cisplatin, a cancer chemotherapy medicine, provides an example of a drug that can turn into something toxic. It is safe when given in saline, but administering it in pure glucose can cause life-threatening kidney damage in patients.

What can hospitals use instead?

The IV fluids currently in short supply are saline and Hartmann’s solution. Three approved Australian suppliers provide them: Baxter Healthcare, B.Braun and Fresenius Kabi.

To respond, the government is authorising several alternative saline brands registered overseas. Under existing legislation, it can do so without those products undergoing the standard Australian quality checks and approval procedure. They will already have been approved in their country of manufacture.

The government is pursuing this option because reformulating medicines intended for saline into other IV fluids may be neither effective nor safe. Australia also lacks adequate capacity to manufacture saline IV fluids domestically.

The Australian Society of Hospital Pharmacists offers guidance for healthcare staff in its Australian Injectable Drugs Handbook on which medicines must be used with particular IV fluids. If saline or Hartmann’s solution is unavailable and shipments of overseas brands have yet to arrive, staff can use this guidance to choose another suitable IV fluid.

Why don't we make it locally?

This IV fluid shortage is another illustration of the difficulties Australia faces because it depends almost entirely on overseas manufacturers for its critical medicines.

Workarounds are available for the present shortage. However, Australia is likely to experience continuing shortages not only of IV fluids, but also of any medicines produced by overseas manufacturers on which it relies. Shortages of this kind endanger Australian lives.

Previously, both I and others have urged the federal government to establish, or support the establishment of, medicines manufacturing in Australia. This could include producing off-patent medicines, with priority given to those used most widely in Australia.

As well as providing secure, high-technology jobs in Australia, this would support the economy and reduce the country’s vulnerability to future global medicine supply disruptions.

Nial Wheate, Professor and Director Academic Excellence, Macquarie University and Shoohb Alassadi, Casual academic, pharmaceutical sciences, University of Sydney.

This article is republished from The Conversation under a Creative Commons license. Read the original article.