Is there a difference between brands of Colchicine?
Australia now has 4 brands of colchicine available. The latest brand making an appearance is Colchicine WGR. Also available is Colcine, Lengout and Colgout.
The Therapeutic Goods Administration (TGA) is the Australian Government agency responsible for regulating medicines. They ensure products are safe, effective and high quality before they are supplied in Australia and they continue to monitor ongoing safety once in the market. In New Zealand this is the role of Medsafe.
Because they have been tested by the TGA and found to be bioequivalent (more on this later), the Pharmaceutical Benefits Scheme (PBS) has all generic colchicine brands as “a-flagged” item, meaning pharmacists may substitute brands (unless the doctor writes “no substitution”). This makes them interchangeable.
You as a patient can request a certain brand of your preference but one is not better than another.
In New Zealand there are two brands available Colgout (subsidised) and Colchicine Indoco but this may change with Pharmac tenders under review. Pharmac has the role of which medications are funded and at what cost.
So why does brand matter?
For many people it doesn’t, but there is anecdotal evidence that patients tolerate different brands differently.
It is very individual as to what works for people.
After doing a bit more research there are a few main obvious differences.
Colcine and Colchicine-WGR
These share exactly the same set of inactive ingredients: pregelatinised maize starch, microcrystalline cellulose, lactose monohydrate, sodium starch glycollate, magnesium stearate.
Colgout and Lengout
These share the same inactive ingredients: magnesium stearate, lactose (or lactose monohydrate), maize starch, and povidone.
Colchicine Indoco (New Zealand Only)
Contains Lactose Monohydrate, Pregelatinised starch, isopropyl alcohol, Povidone, purified water, magnesium Stearate.
To narrow it down further:
- Colcine and WGR have microcrystalline cellulose and sodium starch glycollate
- Colgout/Lengout have povidone + corn (maize) starch.
- Colchicine Indoco/colgout does not contain microcrystalline cellulose. Colchicine Indoco contains isopropyl alcohol and purified water. Povidone is present, like Colgout/Lengout, but absent in Colcine/Colchicine-WGR.
All five contain lactose (or lactose monohydrate) and magnesium stearate.
Other possible reasons there may be a difference in how different brands are tolerated.
Manufacturers can use different:
- Binders
- Disintegrants
- Compression pressures
- Coatings
These change:
- How fast the tablet falls apart.
- How quickly the colchicine dissolves.
- Irritation of the stomach or intestines.
Even small differences can matter because colchicine has a narrow therapeutic window. So small changes in absorption can create noticeable effects like:
- More or less diarrhoea
- Different severity of nausea
- A stronger or weaker “hit” of efficacy
What this means:
AUC - Area Under the Curve, is a measure of total drug exposure over time.If two drugs have similar AUC, they deliver similar amounts of drug into the body.
Generic brands must match the brand name (reference) medication in terms of how much of the drug gets into the bloodstream.
The TGA ensures this happens within a tight regulatory window.
This doesn’t mean generics are 80% or 125% as strong; instead, the confidence interval of the comparison must fall within that range.
But people who are sensitive to colchicine still might notice differences in:
- Onset of action
- Potency
- Side effects
For a medication like colchicine, which is potent and gut-sensitive, even small pharmacokinetic shifts can be noticeable.
While the molecule is the same, the microscopic crystal size of colchicine powder can vary slightly between manufacturers.
This can alter:
- How quickly the colchicine dissolves.
- How strongly it irritates GI tissue.
- Absorption speed.
Most people won’t notice, but sensitive patients might.
Excipients can change:
- How the pill moves through the GI tract.
- Whether it sticks in the oesophagus.
- Irritation of the stomach lining.
- Interaction with transport proteins like P-glycoprotein, which affects colchicine uptake.
Some people may tolerate one excipient profile better.
Colchicine is unusual in that it:
- Has narrow safety margins. (It is still a safe medication to take as directed)
- Strongly interacts with the GI tract.
- Relies heavily on CYP3A4 and P-glycoprotein for metabolism and transport.
Because of this, even tiny changes in absorption can translate into noticeable differences in:
- Nausea
- Diarrhoea
- Abdominal cramping
- Effectiveness for pericarditis
So… are you imagining it? Not at all.
Many patients truly feel different on different colchicine products. It isn’t the active drug that changes, it’s the formulation properties around it.
Further reading:
Australian Prescriber - Pharmaceutical Excipients- where do we begin.
National Library of Medicine - Pharmaceutical Excipients and Drug Metabolism: A Mini-Review
Eurordis.org - Comparative Report
Springer Nature Link - Colchicine Brand Switching in FMF Patients
Oxford Academic - Do all colchicine preparations have the same effectiveness in patients with familial Mediterranean fever?
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