by Alison Poulton, The Conversation

Credit: Pixabay/CC0 Public Domain

Imagine you or your child has attention deficit hyperactivity disorder (ADHD), and after several weeks, or even months, you've found a dose of medication you're happy with.

The problems you previously experienced with ADHD have improved significantly. You're no longer constantly being distracted by your phone, or procrastinating for long periods instead of getting started on a piece of work. Perhaps your child is focusing better at school.

But always in the back of your mind is a worry: what would happen if you or your child ran out of medication? What if your doctor is ill and cannot prescribe it for you? Or what if your medication is no longer available at the pharmacy?

Many Australians with ADHD who take Vyvanse, a drug commonly prescribed to treat the condition, are facing this medication crisis at the moment. The drug has been in short supply in Australia for the past few months.

Getting the dose right

If you have ADHD and are taking medication, it's likely you have reached your current dose by a careful process of medication optimization in consultation with your specialist.

You may have started off with dexamfetamine or methylphenidate tablets, short-acting stimulants that take effect quickly and last for about four hours. During a process called titration, the dose is gradually increased, looking for the dose that works best for you, with the least side effects.

You may have tried modified stimulant formulations—capsules that release the medication more slowly. These include Ritalin LA (long-acting) and Concerta, which both contain methylphenidate and are designed to last either six to eight hours (Ritalin LA) or eight to 12 hours (Concerta).

Or you may have gone straight onto lisdexamfetamine (Vyvanse), a "prodrug" of dexamfetamine. Vyvanse has a protein molecule (lysine) attached which makes it inactive until it has been broken down in the body and releases dexamfetamine. This means a single dose of Vyvanse, like Concerta, may be effective for the entire day.

Although both of these once-daily formulations have similar effects and side effects, you might feel better on one than the other. You might have to try both to find the one which suits you best. Then the dose would be carefully worked out with your specialist.

Shortages have affected different doses

In August 2023 the first shortages occurred in Australia, affecting the 20mg and 30mg strengths.

Then these lower strengths came back and the 50mg was unavailable. Most recently, since December 2023, most pharmacies have only been able to obtain the 20mg and 70mg capsules.

Splitting the dose (for example prescribing 40g to a patient who takes 20g) can be done by mixing the contents of a capsule in water, and reserving half. But this is not recommended by the manufacturer, who will not guarantee the effectiveness of the half dose kept overnight.

Combining doses if available (say 20g and 30g for a patient who normally takes 50g) would require two new prescriptions. These strengths might not be available at the pharmacy the following month, and writing new prescriptions for each patient month by month is not sustainable.

Stimulant prescribing is heavily regulated, with pharmacies allowed to dispense only one month's supply at a time. Prescriptions, which last for up to six months, are retained at the patient's nominated pharmacy and cannot be released to be used elsewhere.

Of course, Vyvanse is not the only ADHD medication. Some people may have been taking Concerta or Ritalin prior to starting Vyvanse, and could revert to their previous dose. Changing medication is not normally a problem, but it might be for someone who responds better to Vyvanse.

Another alternative would be going back to multiple doses of short-acting dexamfetamine. Unfortunately the correct dose of dexamfetamine tablets cannot be calculated from a patient's Vyvanse dose because of the differences in pharmacokinetics—how long it takes for the drug to start working balanced against how quickly it's cleared from the body.

So changing to dexamfetamine would have to involve some flexibility to adjust the dose up or down as needed. This may also have a positive side, because the process depends on the person developing a good understanding of their response to each dose of medication.

There's no ideal solution to this problem. Leaving patients unmedicated is perhaps the worst option because the functional improvement they have come to depend on is withdrawn and the problems associated with untreated ADHD recur. This can leave people in crisis and seeking unproven alternative treatments.

How long will the shortage last?

In Australia, Vyvanse is only available from one company, Takeda, that manufactures it in the United States.

The Therapeutic Goods Administration anticipates the shortages in Australia will last until March or April, depending on the dose.

It can be extremely stressful when your ADHD medication is suddenly unavailable. If you are in this situation and wondering how to manage, remember Vyvanse is not the only formulation available. It's worth getting in touch with your specialist to find out about the alternatives. This could involve an initial period of dose adjustment, but it might be a great deal better than going without.

Provided by The Conversation 

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