AVP-923 and AVP-786

Avanir Pharmaceuticals with drug AVP-923 completed a very successful phase 2 trial for symptoms of agitation in Alzheimer's patients.  Avanir now under the Otsuka umbrella, is conducting two phase 3 trials with the deuterated version of AVP-923, known as AVP-786 for the same patients.  So what are the drug dose differences and exclusion criterias between the successful phase 2 AVP-923 clinical study, and the AVP-786 phase 3 clinical trials for the treatment of agitation in patients with dementia of the Alzheimer's type?

AVP-923  NCT01584440
Phase 2 for the treatment of agitation in patients with dementia of the Alzheimer's type.
Dextromethorphan 20 mg / Quinidine 10 mg
Dextromethorphan 30 mg / Quinidine 10 mg

Exclusion Criteria:

• Patient has other type of dementia (e.g., vascular dementia, frontotemporal dementia, Parkinson's disease, substance-induced dementia).
• Patients with co-existent clinically significant or unstable systemic diseases that could confound the interpretation of the safety results of the study (e.g. malignancy, poorly controlled diabetes, poorly controlled hypertension, unstable pulmonary, renal or hepatic disease, unstable ischemic cardiac disease, dilated cardiomyopathy, certain cardiac conduction abnormalities including QTc prolongation, or unstable valvular heart disease).
• Patients with myasthenia gravis.

AVP-786   NCT02442765, NCT02442778
Phase 3 for the treatment of agitation in patients with dementia of the Alzheimer's type.
Dextromethorphan 28 mg / Quinidine 4.9 mg
Dextromethorphan 18 mg / Quinidine 4.9 mg

Exclusion Criteria:

• Patient has dementia predominantly of non-Alzheimer's type (e.g., vascular dementia, frontotemporal dementia, Parkinson's disease, substance-induced dementia)
• Patients with co-existent clinically significant or unstable systemic diseases that could confound the interpretation of the safety results of the study (e.g., malignancy, poorly controlled diabetes, poorly controlled hypertension, unstable pulmonary, renal or hepatic disease, unstable ischemic cardiac disease, dilated cardiomyopathy, or unstable valvular heart disease)
• Patient with myasthenia gravis

The difference in the exclusions from the phase 2 AVP-923 trial and the deutered version using AVP-786 is that QTc prolongation, which was an exclusion in the phase 2 is not listed in the current phase 3 trials.  The reduction in the dose of quinidine to 4.9 mg from 10 mg could be the prime reason for the two new phase 3 trials not including QTc prolongation as an exclusion criteria.  I expect these two phase 3 trials to recruit at a much faster rate, than the AVP-923 trial achieved. I also expect that patients currently taking AVP-923 for other indications, will eventually switch to the deutered version AVP-786, which has a similar PK profile to AVP-923, favorable dosing, and has a longer patent that extends to 2030 US and 2028 EU. Thank you for reading.