Can I give a missed 400 mg intramuscular aripiprazole (Abilify) injection today to a patient who has not received their scheduled doses since the last appointment and then resume the regular 4‑week dosing schedule?

Can You Give the Missed Abilify 400mg Injection Today?

Yes, you can and should administer the 400mg aripiprazole long-acting injection today, then resume the regular 4-week dosing schedule. 1, 2

Immediate Action Plan

• Administer the 400mg intramuscular injection today as soon as the patient arrives, regardless of how many doses have been missed 1
• Resume the standard every-4-week schedule starting from today's injection date—do not attempt to "catch up" or shift future dates 1
• No oral aripiprazole supplementation is required when restarting after a gap in maintenance dosing 3, 2

Key Pharmacokinetic Rationale

• Aripiprazole has an extremely long half-life of approximately 75 hours (oral) and even longer for the long-acting formulation, meaning therapeutic levels persist for weeks after a missed dose 4, 3
• The general principle for delays less than one half-life is to administer the missed dose immediately and continue with the original schedule 1
• For long-acting injectable biologics with delays <7 days, administer the missed dose as soon as possible and maintain the original schedule 1
• Aripiprazole once-monthly reaches therapeutic plasma concentrations within 7 days of injection and maintains levels for 4-6 weeks 3

Critical Timing Considerations

• The 2-month formulation (Ari2M 960mg) allows reinitiation without loading if <14 weeks have passed since the prior injection 2
• For the monthly 400mg formulation, while specific reinitiation guidelines are not explicitly stated in the evidence, the long half-life and extended therapeutic window support simple resumption of dosing 3, 2
• Median aripiprazole plasma concentrations reach therapeutic levels within 7 days of initiating the long-acting injection, supporting immediate restart 3

When Oral Overlap IS Required (New Starts Only)

• Oral aripiprazole supplementation (10-20mg daily for 14 days) is only necessary when initiating long-acting aripiprazole for the first time, not when resuming after missed maintenance doses 5, 3
• The two-injection start regimen (two 400mg injections plus single 20mg oral dose on day 1) is an alternative initiation strategy but applies only to treatment-naïve patients 5
• Cross-titration from other antipsychotics before initiating aripiprazole long-acting is better tolerated with a >1- to 4-week period versus ≤1 week 3

Safety Monitoring After Restart

• Monitor for extrapyramidal symptoms, particularly akathisia, which is more common with the long-acting formulation than oral aripiprazole 6, 7
• Watch for mild injection site reactions (pruritic reaction, mild erythema), which are typically self-limited 8
• Assess for signs of relapse or symptom worsening over the next 2-4 weeks, as the patient may have had subtherapeutic levels during the gap 8
• No additional laboratory monitoring is required beyond standard maintenance protocols unless clinically indicated 8

Common Pitfalls to Avoid

• Do not require oral supplementation when restarting maintenance therapy—this is only needed for initial treatment starts 3, 2
• Do not delay the injection waiting for oral coverage or additional assessments unless there are acute safety concerns 1
• Do not adjust the dose downward due to the gap in treatment—maintain the established 400mg maintenance dose 3, 6
• Do not administer two injections simultaneously (as in the new-start regimen) when resuming maintenance therapy 5

Adherence Strategies Going Forward

• Implement medication reminders using phone alarms, text message systems, or appointment scheduling apps to prevent future missed doses 4, 1
• Consider the patient's barriers to adherence—transportation issues, work schedules, or ambivalence about treatment may require case management intervention 8
• The 2-month formulation (960mg every 8 weeks) may be appropriate for patients who struggle with monthly visits, though this requires switching protocols 2
• Directly observed therapy and case management strategies (including incentives like transportation vouchers) improve adherence to long-acting injectable regimens 8