From the Guidelines
The effects of 5mg immediate release Adderall are typically felt within 30 minutes after ingestion, with noticeable effects lasting around 3 to 4 hours, as stimulants are rapidly absorbed from the gut and act within the first 30 minutes after ingestion 1.
Onset of Action
The onset of action for immediate release Adderall is relatively quick, usually within 30 minutes, due to its rapid absorption from the gastrointestinal tract. This rapid absorption delivers a quick, large peak in plasma concentration, which is thought to be necessary for the stimulant-related reduction in ADHD symptoms, known as the "ramp effect" 1.
Duration of Action
The duration of noticeable effects for 5mg immediate release Adderall typically lasts about 3 to 4 hours, as the concentration-enhancing and activity-reducing effects of the medication can disappear well before it leaves the plasma, a phenomenon called “clockwise hysteresis” 1.
Half-Life and Clearance
Although the study does not specifically mention the half-life of Adderall, it does mention that the plasma half-life of stimulants can range between 3 hours for MPH and 11 hours for DEX 1. However, for the purpose of this question, we will consider the half-life of Adderall to be around 9-14 hours, as mentioned in general medical knowledge.
Factors Affecting Onset and Duration
Factors that can affect both the onset and duration of Adderall's effects include metabolism, body weight, kidney and liver function, stomach acidity, and whether the medication is taken with food, which can delay absorption 1.
Mechanism of Action
Adderall works by increasing levels of neurotransmitters like dopamine and norepinephrine in the brain, which improves focus and attention, with effects on behavior appearing during absorption, beginning 30 minutes after ingestion 1. It is essential to take Adderall exactly as directed by a healthcare provider to avoid side effects or dependency, and to monitor its effects closely, given the potential for individual variability in response to the medication 1.
From the FDA Drug Label
Following administration of three 5 mg tablets, average maximal dextroamphetamine plasma concentrations (Cmax) of 36. 6 ng/mL were achieved at approximately 3 hours. The average plasma T1/2 was similar for both the tablet and sustained-release capsule and was approximately 12 hours.
- Onset of action: The effects of 5mg immediate release Adderall may be felt in approximately 3 hours, as this is when the average maximal dextroamphetamine plasma concentrations are achieved.
- Duration in system: 5mg immediate release Adderall may stay in the system for approximately 12 hours, as this is the average plasma half-life (T1/2) of the drug 2.
From the Research
Onset of Effects
- The onset of effects for 5mg immediate release Adderall can be expected to occur within 2 to 3 hours after administration, as IR formulations typically provide a Tmax from 2 to 3 hours 3.
- This rapid absorption is due to the high absolute bioavailability of oral amphetamine, which is then followed by extensive metabolism involving multiple enzymes 3.
Duration of Action
- The duration of action for 5mg immediate release Adderall can vary depending on factors such as age and body weight, but in general, the plasma half-life (T1/2) for amphetamine is around 7 hours in children and 10 to 12 hours in adults 3.
- As a result, the effects of 5mg immediate release Adderall can be expected to last for several hours, although the exact duration may vary from person to person.
Elimination
- Amphetamine is extensively metabolized in the body, with some metabolic pathways exhibiting stereoselective biotransformations favoring the l-isomer substrate 3.
- The elimination of amphetamine from the body is primarily through the kidneys, with the majority of the drug being excreted in the urine within 24 to 48 hours 3.
Individual Variability
- It's worth noting that individual variability in the pharmacokinetics of amphetamine can be significant, with factors such as body weight, age, and renal function influencing the drug's absorption, distribution, metabolism, and elimination 3, 4, 5, 6, 7.
- As a result, the onset and duration of effects for 5mg immediate release Adderall can vary significantly from person to person, and individual factors should be taken into account when determining the optimal dosage and administration schedule.