BOSTON ( TheStreet) -- Let's kick off this week's Biotech Stock Mailbag with talk of new drug launches.

RMB77 asks, "Do you have any indication about how well Avanir Pharmaceuticals ( AVNR) is doing with the launch of Nuedexta? I know it's early, but I was hoping you've heard something to tell us if doctors are prescribing the drug."

Avanir only began selling Nuedexta at the end of January as a treatment for pseudobulbar affect (PBA) -- uncontrollable bouts of laughter and crying caused by certain neurological conditions. Nuedexta prescriptions to date are "modest" but "too early to draw conclusions," says Canaccord Genuity analyst Ritu Baral, who is one of Wall Street's more vocal Avanir bulls.

An institutional investor who's short Avanir describes the Nuedexta launch to me as "slow," which supports his thesis that the drug will be a commercial disappointment.

Nuedexta total scripts totaled 181 for the week ended March 18 (the most recent data available), according to IMS Health. That's the highest weekly total since Nuedexta's launch but only represents 5% growth over the 172 total scripts written for the drug for the week of March 11. Overall, 811 Nuedexta prescriptions have been written from Jan. 21 through March 18, according to IMS.

The number of Nuedexta prescriptions is growing every week but the sequential (week over week) growth is erratic -- not unusual for a drug in the infancy of a launch although the 5% growth for the week of March 18 is a concern if that trend continues.

Based on these script data, the Avanir short-seller mentioned above estimates total Nuedexta sales of $372,000 through March 18, which suggests Avanir will have a tough time meeting analysts' $1.5 million Nuedexta consensus revenue estimate for the company's fiscal second quarter, which ended Thursday.

Fiscal second-quarter sales may not matter much, but Avanir needs to quickly ramp Nuedexta sales if it's going to meet analysts' consensus revenue estimate of $30 million for the end of the company's fiscal year in September, the short-seller says. He clearly doesn't think Nuedexta makes it, which is why he's short Avanir.

Canaccord analyst Baral advised investor clients to chill out and not sweat the early Nuedexta metrics so much.

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