What is the recommended dosing for adding Cymbalta (duloxetine) to a patient already taking Zyprexa (olanzapine) 5mg?

Duloxetine Dosing When Adding to Olanzapine 5mg

The recommended dosing for adding duloxetine to a patient already taking olanzapine 5mg is to start with duloxetine 30mg once daily for 1 week before increasing to 60mg once daily. 1

Initial Dosing and Titration

• Start duloxetine at 30mg once daily for the first week to minimize side effects 1
• After one week, increase to the target dose of 60mg once daily if tolerated 1
• Avoid starting at higher doses as this increases risk of adverse effects 2

Monitoring Requirements

• Assess for adverse effects at each follow-up visit, particularly those related to higher doses 2
• Monitor blood pressure regularly as duloxetine can cause modest hypertension 3, 2
• Evaluate therapeutic response using standardized scales for depression or pain 2
• Watch for potential additive sedation when combining with olanzapine 1

Potential Drug Interactions

• Both medications can cause sedation, potentially having an additive effect 1
• Be cautious about combining with benzodiazepines, as olanzapine plus benzodiazepines has been associated with respiratory depression 1
• The combination may increase the risk of orthostatic hypotension 1

Special Considerations

• Duloxetine is not recommended for patients with creatinine clearance <30 mL/min 2
• For elderly patients or those with hepatic impairment, consider lower starting doses of both medications 1
• If treatment needs to be discontinued, taper the dose gradually to minimize withdrawal symptoms 2

Olanzapine Considerations

• The current olanzapine dose of 5mg daily is within the recommended range for most indications 4
• Olanzapine can be used at doses of 2.5-10mg daily depending on the indication 4
• Higher doses of olanzapine (>5mg) may increase the risk of metabolic side effects 5

Efficacy Considerations

• Duloxetine at 60mg daily has demonstrated efficacy for depression, neuropathic pain, and fibromyalgia 6
• Lower doses of duloxetine (<60mg daily) may not be as effective for these conditions 6
• The combination of olanzapine with an antidepressant may be particularly effective for treatment-resistant depression 7

Common Adverse Effects to Monitor

• Nausea is the most common treatment-emergent adverse event with duloxetine 8
• Sedation and drowsiness are common with olanzapine 1
• Hyperglycemia can develop rapidly after starting or increasing olanzapine, even within days 5
• Weight gain is common with olanzapine and should be monitored 4

Clinical Pearls

• Duloxetine capsules should be swallowed whole and not crushed or chewed 2
• Taking duloxetine with food may help reduce nausea 2
• If the patient experiences intolerable side effects, consider returning to the lower dose before attempting to increase again 1
• For treatment-resistant depression, the combination of olanzapine and an antidepressant has shown better efficacy than either drug as monotherapy 7