Unfortunately there is no universally applicable answer to this question. Your own unique physiology and daily responsibilities will determine whether Adderall IR vs Adderall XR is the better fit.
Let this information guide you (or your physician’s) decision.
- Release mechanism. The key difference between Adderall XR and Adderall IR is the release mechanism. An Adderall XR capsule contains two flavors of amphetamine containing beads engineered to give a two pulses of amphetamine 1, which prolongs release.
- Duration. Adderall IR lasts 6 hours, whereas Adderall XR lasts about 10-12 hours.
- Peak concentration (Cmax and Tmax). Adderall XR peaks ~7 hours post-ingestion 2. That’s usually when people start to notice a decrease in efficiency of the drug and often report a crash a few hours later.
- Physical appearance. Adderall IR comes as a blue or orange tablet, whereas Adderall XR is a capsule that contains many beads. These beads are filled with amphetamine.
- Chemical properties. Adderall IR and Adderall XR are chemically identical. They contain the same blend of amphetamine salts in identical ratios (1/4 l-amphetamine salts, 3/4 d-amphetamine salts)3.
- Inactive ingredients.
- Adderall XR has the following inactive ingredients:
- sugar spheres
- triethyl citrate
- hydroxypropyl methylcellulose
- gelatin capsules
- opadry beige
- methacrylic acid copolymer
- Adderall IR contains these inactive ingredients:
- microcrystalline cellulose
- colloidal silicon dioxide
- magnesium stearate
- Adderall XR has the following inactive ingredients:
Which is Better – Instant-Release or Extended?
My experience has been that the IR and XR formulations serve two difference functions. Adderall IR provides a burst of productivity that is relatively short-lived (6 hours)4. Adderall XR lasts longer (10 – 12 hours).
So Adderall XR is more appropriate if you need enhanced concentration for a sustained amount of time. For example, if you’re an attorney who needs to be “on” for 10 hours a day, Adderall XR may be the better choice.
An added benefit of Adderall XR is that the effects of the drug are “smoother.” The instant-release variety can give you more of a jolt that some people need to get things done5. But for others this excess stimulation can worsen adverse effects like anxiety and hypertension.
But there are big advantages to Adderall IR, too. I actually prefer Adderall IR to Adderall XR because it affords more control over timing the effects. I am most productive when I work for 4-6 stretches and then take a long break or a nap. It can be hard to fall asleep on amphetamines 6. So it makes sense to take Adderall IR so that I have more control over when the drug is in my system.
Adderall IR vs XR Drug Delivery Mechanism
The FDA states it best 7:
ADDERALL XR™ is a once daily extended-release, single-entity amphetamine product. ADDERALL XR™ combines the neutral sulfate salts of dextroamphetamine and amphetamine, with the dextro isomer of amphetamine saccharate and d,l-amphetamine aspartate monohydrate. The ADDERALL XR™ capsule contains two types of drug-containing beads designed to give a double-pulsed delivery of amphetamines, which prolongs the release of amphetamine from ADDERALL XR™ compared to the conventional ADDERALL® (immediate release) tablet formulation.
Adderall XR is better for individuals who:
- Are sensitive to the effects of the drug (more gradual onset = reduced adverse effects)
- Need to be productive for long stretches of time
- Have a history of substance abuse or are prone to addiction
Adderall IR is better for individuals who:
- Are prone to insomnia
- Like more control over timing the drug
- Benefit from the added “kick” of instant release
- Are not prone to addiction or substance use
- Spencer TJ, Abikoff HB, Connor DF, et al. Efficacy and safety of mixed amphetamine salts extended release (adderall XR) in the management of oppositional defiant disorder with or without comorbid attention-deficit/hyperactivity disorder in school-aged children and adolescents: A 4-week, multicenter, randomized, double-blind, parallel-group, placebo-controlled, forced-dose-escalation study. Clinical therapeutics. 2006; 28(3): 402-18. ↩
- McGough JJ, Biederman J, Greenhill LL, et al. Pharmacokinetics of SLI381 (ADDERALL XR), an extended-release formulation of Adderall. Journal of the American Academy of Child and Adolescent Psychiatry. 2003; 42(6): 684-91. ↩
- Tulloch SJ, Zhang Y, McLean A, Wolf KN. SLI381 (Adderall XR), a two-component, extended-release formulation of mixed amphetamine salts: bioavailability of three test formulations and comparison of fasted, fed, and sprinkled administration. Pharmacotherapy. 2002; 22(11): 1405-15. ↩
- Biederman J, Lopez FA, Boellner SW, Chandler MC. A randomized, double-blind, placebo-controlled, parallel-group study of SLI381 (Adderall XR) in children with attention-deficit/hyperactivity disorder. Pediatrics. 2002; 110(2 Pt 1): 258-66. ↩
- Sallee FR, Smirnoff AV. Adderall XR: long acting stimulant for single daily dosing. Expert review of neurotherapeutics. 2004; 4(6): 927-34. ↩
- Wigal SB, McGough JJ, McCracken JT, et al. A laboratory school comparison of mixed amphetamine salts extended release (Adderall XR) and atomoxetine (Strattera) in school-aged children with attention deficit/hyperactivity disorder. Journal of attention disorders. 2005; 9(1): 275-89. ↩
- http://www.accessdata.fda.gov/drugsatfda_docs/label/2004/021303s005lbl.pdf ↩