Vyvanse (Lisdexamfetamine) is an amphetamine medication used for the treatment of ADHD (attention deficit hyperactivity disorder).
It is a prodrug, meaning that is pharmacologically inactive on its own and needs to be metabolized within the body to the active drug, which in this case, is dextroamphetamine.
Dextroamphetamine is an amphetamine that will show up in urine drug tests that are looking for 'amphetamine', which is most of them.
In fact, amphetamines are one of the five classes of drug that are looked for on 'standard five-panel' drug screenings.
How long it will take your body to completely metabolize and eliminate Vyvanse (specifically, dextroamphetamine) will vary by individual.
Certain factors such, such as your age, kidney function and the acidity of your urine (more on this later), will influence elimination time.
Half-Life Of Vyvanse
A key characteristic in determining how long a given drug will stay in your system is its 'half-life'.
The half-life of a drug, in simple terms, is the length of time it takes to metabolize or eliminate 50% of it.
So, as an example, consider a drug with a half-life of 8 hours. The following chart represents how much of the drug will be left in your system over time.
'Drug X' Concentration Over Time (Half-Life 8 Hours)
|Time (Hours)||Drug Remaining|
|Initial (0 Hours)||100%|
|1 Half-Life (8 Hours)||50%|
|2 Half-Lives (16 Hours)||25%|
|3 Half-Lives (24 Hours)||12.5%|
|4 Half-Lives (32 Hours)||6.25%|
|5 Half-Lives (40 Hours)||3.125%|
|6 Half-Lives (48 Hours)||1.56%|
In general, it takes around five to six half-lives for a drug to be considered completely eliminated for your system, and be present in low enough concentrations that it won't produce a 'positive' test on urine drug screens (this will vary based on the specificity of the test, however).
The prescribing information for Vyvanse lists the half-life dextroamphetamine (the active metabolite) as 12 hours:
The mean plasma elimination half- life of dextroamphetamine was about 12 hours after oral administration of lisdexamfetamine dimesylate.
With an average half-life of 12 hours, we would expect for the drug to take around 60-72 hours (translating to five to six half-lives) for it to be completely eliminated from the body.
Vyvanse Concentration Over Time Chart
|Time (Hours)||Drug Remaining|
|Initial (0 Hours)||100%|
|1 Half-Life (12 Hours)||50%|
|2 Half-Lives (24 Hours)||25%|
|3 Half-Lives (36 Hours)||12.5%|
|4 Half-Lives (48 Hours)||6.25%|
|5 Half-Lives (60 Hours)||3.125%|
|6 Half-Lives (72 Hours)||1.56%|
As mentioned, there are several factors aside from the known half-life of a drug that can influence how quickly it is eliminated from your system.
These factors include:
- Urinary pH
- Kidney function
- How long you have been taking the drug
In terms of urinary pH, elimination of all amphetamines are known to be affected by how acidic or basic your urine is.
Amphetamines are basic (i.e. have a pH greater than 7), and without getting into the science of this, their urinary excretion decreases as the pH increases. In other words, if your urine is basic, it will take longer to eliminate.
Conversely, acidification of the urine speeds elimination.
One study reported the following regarding amphetamine elimination and urine pH:
When urine is acidified the excretion of unchanged amphetamine is approximately four times that of the deaminated metabolites, hippuric and benzoic acid. However, when urine is alkaline, the excretion of these metabolites is approximately equal to that of the unchanged drug.
Acidifying the urine can work very well to increased amphetamine elimination rates. Drugs, like ammonium chloride (which acidifies the urine), have been used in cases of amphetamine toxicity. It has also been reportedly used in those using the drug illicitly to beat drug tests.
The other factors listed above are of consequence too. For example, for chronic amphetamine users, detection times on urine drug tests are far longer due to the drug accumulation in the body. Studies report that chronic users may test positive for up to 7 to 10 days.
Since there are so many factors that will determine how long Vyvanse could potentially be detected on a urine drug test, it is impossible to give an exact figure.
Nevertheless, the following chart neatly summarized what you could generally expect.
Vyvanse Detection Times (Urine Drug Screening)
|Type Of User||Detection Time|
|Non-Chronic User||2 to 3 days|
|Chronic User||7 to 10 days|
*A chronic user is an individual taking the drug on a daily basis for at least a few weeks.
In the situation you have described, taking Vyvanse for 2 to 3 weeks and wondering if it will show positive on a urine test on the morning of the third day, you are right at the edge of that detection limit. If you test positive or don't, it wouldn't be surprising either way.
If you have been prescribed Vyvanse by your physician, be sure to bring proof of this to your employer, or whoever is testing you. As long as is it a legitimate use of the medication, you shouldn't have any issues regardless of your testing.
Vyvanase is metabolized in the body to the active substance, dextroamphetmine. Dextroamphetamine has been reported to be detectable on urine drug screenings up to 2 to 3 days in non-chronic users, and up to 7 to 10 days in chronic users.
- ^ Lisdexamfetamine Dimesylate (Vyvanse), A Prodrug Stimulant for Attention-Deficit/Hyperactivity Disorder. PubMed
- Mayo Clinic Urine Drug Screening: Practical Guide for Clinicians.
- PubMed The ABCD of clinical pharmacokinetics.
- PubMed OBJECTIVE TESTING – URINE AND OTHER DRUG TESTS.
- AccessFDA Vyvanse Prescribing Information.
- PubMed Influences of urinary pH on the pharmacokinetics of three amphetamine-type stimulants using a new high-performance liquid chromatographic method.
- PubMed The excretion of dexamphetamine and its derivatives.
- ToxNet Amphetamine Monograph.
- PubMed Commonly prescribed medications and potential false-positive urine drug screens.