What are the recommended pharmacologic treatments and dosing for a patient with anorexia nervosa binge‑eating/purging type after weight restoration to at least 85 % of ideal body weight?

Pharmacologic Treatment for Anorexia Nervosa, Binge-Eating/Purging Type After Weight Restoration

No medications are approved or routinely recommended for anorexia nervosa after weight restoration, and psychotherapy remains the primary treatment; however, if pharmacologic adjuncts are considered, olanzapine 5 mg once daily is the first-line option, with fluoxetine 60 mg daily reserved only for preventing relapse after weight restoration. 1

Primary Treatment Framework

Psychotherapy, not medication, is the cornerstone of treatment even after weight restoration to ≥85% ideal body weight. 1

• Eating disorder-focused psychotherapy targeting normalization of eating behaviors, maintenance of restored weight, and reduction of fear of weight gain must continue as the primary intervention. 1
• For adolescents and emerging adults with involved caregivers, family-based treatment remains the recommended approach even post-weight restoration. 1, 2
• Multidisciplinary coordination among medical, psychiatric, psychological, and nutritional expertise is mandatory throughout the entire treatment duration. 2, 3

Mandatory Pre-Medication Safety Assessment

Before initiating any psychotropic medication, obtain an electrocardiogram because QTc prolongation is common in anorexia nervosa and certain psychiatric drugs further prolong the QTc interval. 1

• Comprehensive metabolic panel including electrolytes is required prior to medication initiation. 1
• Baseline vital signs with orthostatic blood pressure measurement must be documented. 1
• Complete blood count should be obtained before any pharmacologic intervention. 1
• Repeat ECG monitoring is advised when prescribing medications with QT-prolonging potential. 1

Pharmacologic Options (If Adjunctive Treatment Is Pursued)

First-Line Adjunct: Olanzapine

Initiate olanzapine at 5 mg once daily as the starting dose when adjunctive pharmacotherapy is used alongside ongoing psychotherapy and nutritional monitoring. 1

Relapse Prevention: Fluoxetine

Fluoxetine may reduce relapse risk in adults after weight restoration, though it has no role in acute weight restoration itself. 4

• This represents a distinct indication from bulimia nervosa, where fluoxetine 60 mg daily is FDA-approved and first-line. 1
• The American Psychiatric Association emphasizes that current evidence does not support routine pharmacologic treatment for weight restoration in anorexia nervosa. 1

Comorbid Depressive Symptoms: Mirtazapine

Mirtazapine 7.5 mg to 30 mg at bedtime may be used when prominent depressive symptoms persist after weight restoration, providing both antidepressant and appetite-stimulating effects. 1

• Selective serotonin reuptake inhibitors may be beneficial for treating comorbid anxiety, depression, and obsessive-compulsive behaviors. 5

Critical Pitfalls to Avoid

Do not use appetite-stimulating agents approved for cancer-related anorexia (megestrol acetate, dexamethasone) in anorexia nervosa, as the underlying pathophysiology and treatment goals fundamentally differ. 1

• Quetiapine is not an effective augmentation agent even in related psychiatric disorders and should be avoided. 1
• Oral contraceptives should not be used to "treat" amenorrhea in anorexia nervosa, as they create false reassurance with withdrawal bleeding but do not restore spontaneous menses and may compromise bone health. 1

Ongoing Monitoring Requirements

Regular assessment of weight, vital signs, and laboratory parameters is essential throughout the treatment duration, even after weight restoration. 2, 5

• Individualized goals for maintaining target weight must be monitored continuously. 2
• Quantification of eating and weight control behaviors should occur weekly. 1
• Repeat metabolic panels and ECGs as clinically indicated, particularly if medications are continued. 1, 5

Evidence Quality and Limitations

The literature on pharmacologic treatment for anorexia nervosa is sparse and inconclusive. 4 No medications have demonstrated efficacy for weight restoration, and most patients fail to benefit from available medications. 6 The American Psychiatric Association's 2023 guidelines explicitly state that no medications are approved for anorexia nervosa and current evidence does not support routine pharmacologic treatment. 1 This stands in stark contrast to bulimia nervosa, where fluoxetine 60 mg daily has strong evidence and FDA approval. 1