Alternative Medication for Fibromyalgia and Generalized Anxiety Disorder After Duloxetine Discontinuation
Pregabalin 150 mg twice daily (300 mg/day total) is the optimal alternative medication for this patient, as it effectively treats both fibromyalgia pain and generalized anxiety disorder while having a weight-neutral or modest weight gain profile that is less problematic than alternatives in a patient with morbid obesity. 1
Rationale for Pregabalin as First Choice
Pregabalin has Level Ia, Grade A evidence for reducing pain in fibromyalgia, with patients more likely to achieve 30% pain reduction (RR 1.38,95% CI 1.25 to 1.51) compared to placebo 1
Pregabalin demonstrates anxiolytic effects that address the patient's generalized anxiety disorder, making it a dual-purpose medication 2
The recommended dosing starts at 75 mg twice daily, increasing to 150 mg twice daily within 1 week based on tolerance, with no additional benefit at 600 mg/day but increased dose-dependent adverse reactions 1
Pregabalin improves sleep quality, which is particularly relevant given the patient is already taking cyclobenzaprine (Flexeril) for sleep 1
Why Not Other First-Line Options
Amitriptyline should be avoided in this patient despite its Level Ia, Grade A evidence for fibromyalgia, because tricyclic antidepressants cause significant weight gain, which is contraindicated in a patient with morbid obesity 1
Milnacipran (Savella) is another SNRI like duloxetine and may cause similar side effects including hot flashes, making it a poor choice after duloxetine failure due to tolerability issues 3, 1
The patient is already taking cyclobenzaprine (Flexeril), so adding another sedating medication like amitriptyline would create excessive sedation and anticholinergic burden 1
Important Monitoring and Titration
Start pregabalin at 75 mg twice daily for the first week to assess tolerability, particularly monitoring for dizziness and somnolence 1
Increase to the target dose of 150 mg twice daily (300 mg/day total) after one week if tolerated 1
Do not escalate beyond 450 mg/day, as higher doses provide no additional benefit but significantly increase adverse events 1
Reassess pain levels, anxiety symptoms, and side effects every 4-8 weeks to evaluate treatment efficacy 1
Critical Pitfalls to Avoid
Do not add gabapentin if pregabalin is chosen, as they bind to identical targets with the same mechanism, making this combination pharmacologically redundant 1
Do not prescribe strong opioids or corticosteroids for fibromyalgia, as they lack efficacy and cause significant harm 3, 1
Avoid escalating pregabalin beyond 450 mg/day, as this provides no additional benefit but increases adverse events including weight gain, dizziness, and peripheral edema 1
If Pregabalin Fails or Is Not Tolerated
Second option: Tramadol is recommended for pain management with Level Ib, Grade A evidence when first-line medications are ineffective, though it should be used with caution given opioid-related risks 3, 1
Consider non-pharmacological interventions as essential adjuncts: heated pool therapy with or without exercise (Level IIa, Grade B evidence) and cognitive behavioral therapy for the anxiety component (Level Ia, Grade A evidence) 1, 4
If partial pain relief is achieved with pregabalin alone, consider adding tramadol rather than switching completely, as combination therapy may provide greater benefit 1
Addressing the Obesity Concern
Pregabalin can cause weight gain in some patients, but the effect is generally modest compared to tricyclic antidepressants like amitriptyline 1
The patient should be counseled about this potential side effect and encouraged to engage in the graduated exercise program recommended for fibromyalgia, which addresses both pain and weight management 1, 4
Monitor weight at each follow-up visit and consider dose reduction or medication switch if significant weight gain occurs (>5% body weight) 1