About the shortage of Zimstat (simvastatin) 5 mg tablets

Pharmaceutical company Alphapharm has told us that the shortage of Zimstat (simvastatin) 5 mg tablets has been extended until the end of April 2026. Although other brands and strengths of simvastatin will remain available, Zimstat 5 mg is the only tablet of that strength supplied in Australia. 

Simvastatin is used:

• as an adjunct to diet for treatment of hypercholesterolaemia
• in patients at high risk of coronary heart disease (CHD) (with or without hypercholesterolaemia) including patients with diabetes, history of stroke or other cerebrovascular disease, peripheral vessel disease, or with existing CHD to reduce the risk of cardiovascular death, major cardiovascular events including stroke, and hospitalisation due to angina pectoris
• as an adjunct to diet in adolescent boys and girls who are at least one year post-menarche, 10-17 years of age, with heterozygous familial hypercholesterolaemia (HeFH). 

To help patients have continuous access to the medicine, we have extended the Serious Scarcity Substitution Instrument (SSSI) to 31 May 2026. The SSSI allows a pharmacist to dispense an equivalent quantity of simvastatin 10 mg tablets, if appropriate, without a new prescription. 

For the substitute dose, the patient should take half a 10 mg simvastatin tablet in place of the 5 mg tablet prescribed. This will involve breaking or cutting the 10 mg tablet in half.

See below for information about the SSSI for patients, pharmacists and prescribers.

Up-to-date information about the shortage is published on the Medicine Shortage Reports Database - external site (search for ‘Zimstat’).

Information for patients

If the Zimstat (simvastatin) 5 mg tablets your doctor has prescribed are not available, your pharmacist can substitute simvastatin 10 mg tablets without needing a new prescription. This may mean you will need to switch between different brands or strengths. Please note:

• The substitute medicines contain a different strength of the same active ingredient that your doctor prescribed, and the pharmacist will supply the correct total dose.
• All of the products contain the same medicine (simvastatin) and are taken by mouth, but the strength is different.
• Talk to your doctor or pharmacist if you have any questions about this substitution.
• As excipients (inactive ingredients) vary between brands, tell your pharmacist if you are allergic or intolerant to certain ingredients. You can also find information about excipients in the Consumer Medicine Information (CMI) leaflet for the medicine, which is available from your pharmacist or on the TGA website (go to ‘Search for health products on our register’ on the homepage).

If your pharmacist gives you simvastatin 10 mg tablets as a substitute, they will explain to you the differences and how to take them:

• The tablets are a different strength and might look different.
• You must break or cut a 10 mg simvastatin tablet exactly in half and take only one of the halves to get a 5 mg dose.

If you are unable to fill your prescription or do not consent to the substitution, speak to your doctor about other options for your situation.

Information for pharmacists

The SSSI allows you to substitute simvastatin 10 mg tablets for someone with a prescription for simvastatin 5 mg tablets. You can do this without prior approval from the prescriber if you follow the Specific permitted circumstances (in Schedule 1) and General permitted circumstances (in Schedule 2) of the SSSI.

You are encouraged to use your professional and clinical judgement to determine whether substitution is suitable for the patient and to gain their consent. Always refer patients to their prescriber if:

• substitution is inappropriate
• an appropriate substitutable medicine is not available.

Do this noting that inadvertent overdose may occur if the tablet is inaccurately split. 

Situations where substitution is inappropriate could include when a patient:

• does not have the dexterity needed to comfortably break or cut the 10 mg tablets, if needed, either because of their age or medical conditions
• has cognitive, visual or hearing impairments that could make substituting their medicine difficult.

When you use the SSSI to substitute the scarce and substitutable medicine: 

• you must instruct the patient or carer on how to take or give the substitute tablet, or refer them to their prescriber or GP for guidance
• as some brands of simvastatin 10 mg tablets are not scored, to ensure accurate dosing, you should consider whether the patient may need an appropriate method, such as using a pill cutter, to accurately divide the tablet
• you can use Consumer Medicines Information (CMI) leaflets to help explain the substitution to patients or their carers and to get their consent; you may need to use translation services, a carer or organisations such as a local Aboriginal Community Controlled Health Organisation (ACCHO) to ensure the patient fully understands the situation. 

Inform the prescriber by email, fax or phone as soon as is practical after you make the substitution. 

You can find information on Pharmaceutical Benefits Scheme (PBS) subsidy arrangements for medicines substituted using an SSSI on the PBS website.

Information for prescribers

Consider the current shortage of simvastatin 5 mg tablets when prescribing for your patients, particularly when initiating new patients. 

Your patients may need to switch between different brands or strengths of simvastatin tablets when the prescribed medicine is unavailable.

With the SSSI in place, a pharmacist may substitute the prescribed Zimstat (simvastatin) 5 mg tablets with 10 mg simvastatin tablets and give information and guidance on how to administer the substitute product, or they may recommend the patient contact you for this information.

The pharmacist will refer the patient to you if:

• an appropriate substitutable medicine is not available
• they feel a medicine is not clinically appropriate for a patient, or alternative treatments other than substitution may be more appropriate
• the patient does not consent to the substitution
• you have noted on the prescription that substitution is not permitted.

The pharmacist will also refer the patient to you if substitution is inappropriate, for example if the patient:

• does not have the dexterity needed to comfortably break or cut the 10 mg tablets, if needed, either because of their age or medical conditions
• has cognitive, visual or hearing impairments that could make substituting their medicine difficult.

They do this noting that inadvertent overdose may occur if the tablet is inaccurately split.

General information

Please note that the dates given for this shortage may change and we encourage you to check the Medicine shortage reports database - external site for updates about the supply of Zimstat (simvastatin) 5 mg tablets.

Please also keep in mind that we can work with pharmaceutical companies to communicate information about medicine shortages to health professionals and patients, but we cannot compel companies to increase supply.

While we can suggest approaches to manage the supply of medicines during shortages, we do not have the power to regulate the clinical decisions of health professionals.

We will continue to monitor the supply of Zimstat (simvastatin) 5 mg tablets and work with the supplier to update this advice if needed.

Reporting problems

Consumers and health professionals are encouraged to report problems with medicines or vaccines. Your report will contribute to the TGA's monitoring of these products.

The TGA cannot give advice about an individual's medical condition. You are strongly encouraged to talk with a health professional if you are concerned about a possible adverse event associated with a medicine or vaccine.