MJB ADHD · Static reading view · Interactive version
Status: sourced · Content checked 2026-10-06
Record product differences precisely. A repeatable difference is worth raising even when the explanation is unknown — but observation and mechanism are different claims.
Some people respond differently to two products containing the same active medicine. That observation is worth recording precisely. The explanation is a separate question: product, strength, dose timing, food, other medicines, sleep and expectation can all play a part.
Matthew reports much better function on Amfexa 10 mg and 20 mg tablets than on earlier generic dexamfetamine 5 mg tablets, which he says he rarely collected because they did little.
AUTHOR-ACCOUNTHe suspects a tablet ingredient (povidone or a related compound) reduces his response. No test has isolated that ingredient; it remains a hypothesis — see Open research questions.
| Explanation | How you might tell |
|---|---|
| Different dose actually taken | Compare dispensing records and dose logs |
| Different release or absorption | Timing of onset and wearing-off, recorded the same way each day |
| Ingredient difference | Same strength, same timing, two products, consistent difference over repeated use — then discuss with a pharmacist |
| Expectation | Effects reported within seconds or minutes of swallowing are too fast for absorption |
| Other variables | Food, sleep, pain, other medicines on the same days |
Log: product name, manufacturer, strength, dose, time taken, food, other medicines, time of first noticeable effect, time it wore off, benefit, unwanted effects. Ask a pharmacist to confirm the exact product and its ingredient list, and ask your prescriber whether specifying the same product each time is clinically appropriate.
Amfexa is not an "isomalt-only" tablet: the 10 mg tablet lists isomalt, magnesium stearate and yellow iron oxide; the 20 mg tablet lists isomalt, magnesium stearate and red iron oxide; and the 5 mg tablet also contains crospovidone.
W4Specifying a product by brand is ordinary practice where there is a reason for it. Some NHS shared-care agreements already advise prescribing dexamfetamine by brand for ADHD.
One integrated care board's adult ADHD shared-care agreement states that only the Amfexa brand is licensed to treat ADHD and that generic 5 mg dexamfetamine tablets are not, and advises against prescribing generically.
P1That is another area's document, not a rule everywhere — ask what your local agreement says.
A product difference in one person does not identify its cause. Formulation science for these tablets in adults is not well studied.
The manufacturer of the generic 5 mg tablets previously dispensed has not been identified; dispensing history would show it.