Methylphenidate–Amphetamine Dose Conversion Guidelines

Conversion Ratios

The recommended conversion uses a 1.5 : 1 to 2 : 1 methylphenidate‑to‑amphetamine ratio, meaning that 60 mg of mixed amphetamine salts corresponds to approximately 90–120 mg of methylphenidate. This ratio is based on guideline‑recommended starting doses and titration increments rather than direct bioequivalence trials. 1
The theoretical equivalent calculated with the 1.5 : 1 ratio is 90 mg methylphenidate for a 60 mg amphetamine dose. 1

Starting doses reflect the conversion ratio: methylphenidate is typically initiated at 5 mg, while amphetamine starts at 2.5 mg (approximately a 2 : 1 ratio).
Dose‑escalation increments follow the same proportionality: methylphenidate is increased by 5–10 mg per step, whereas amphetamine is increased by 2.5–5 mg per step. 1
When higher doses are needed, increase methylphenidate by 10–20 mg weekly if symptom control remains inadequate and tolerability is acceptable. 1

The FDA‑approved maximum for amphetamine‑type stimulants is 40 mg/day; clinicians may consider doses up to ~0.9 mg/kg (≈40 mg) in adults when clinically justified. 2
The FDA‑approved maximum for methylphenidate is 60 mg/day; doses above this are occasionally used only after lower doses fail and no adverse effects are observed. 1

Prior to exceeding standard maxima, document failure of lower doses and confirm that the higher dose does not produce adverse effects such as weight loss, elevated blood pressure, or agitation. 2
Continuous monitoring for tolerance is required when doses surpass standard limits. 2
Obtain baseline and quarterly vital signs (blood pressure, pulse, weight, height) in adults before initiation and during ongoing therapy. 2

Stop dose escalation if, after 4 weeks at a given dose, symptoms have not improved; consider switching medications or adding behavioral interventions. 2
Screen for stimulant diversion and assess adherence before prescribing supra‑maximum doses; ensure that apparent treatment failure is not due to non‑adherence, diversion, or tolerance. 2

Dose‑response is not linear: higher doses may reach a therapeutic plateau while side‑effects increase, so clinicians should avoid assuming greater benefit with higher amounts. 2
If symptoms persist despite adequate dosing, re‑evaluate the diagnosis and assess for comorbid conditions (e.g., anxiety, mood disorders) that may influence treatment response. 2

The 1.5 : 1–2 : 1 conversion ratio is derived from expert‑consensus dosing guidelines, not from head‑to‑head bioequivalence studies; therefore, clinical titration based on individual response remains the gold standard. 1