GW Pharmaceuticals PLC reported Tuesday afternoon that sales of its cannabis-derived epilepsy drug more than doubled from the previous quarter, sending shares spiking more than 11% higher in after-hours trading.

GW Pharmaceuticals GWPH, +1.97% reported second-quarter sales of $68.4 million for Epidiolex, which uses cannabidiol, a compound present in cannabis plants to treat certain forms of epilepsy. Wall Street analysts had forecast Epidiolex sales of $40.9 million, after GW Pharma reported sales of $33.5 million in the first quarter.

“We are pleased to report a strong second quarter of sales of Epidiolex in the U.S., reflecting high demand by U.S. patients, increased prescribing by health care providers, and ongoing progress in payer-coverage determinations,” GW Pharma Chief Executive Justin Glover said in a statement.

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Since the drug’s launch, the company said more than 12,000 patients have received prescriptions for the medicine and it has been dispensed to 2,500 doctors.

Overall, the company reported second-quarter net income of $79.8 million, or 21 cents a share, compared with losses of $84 million, or 25 cents a share, in the year-ago period. The United Kingdom-based company’s net income benefited from a $104.1 million gain on the sale of one of its intangible assets. Revenue rose to $72 million from $3.3 million in the year-ago period.

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Analysts surveyed by FactSet had estimated overall earnings of a penny a share on revenue of $47 million.

For the third quarter, analysts model losses of 14 cents a share on sales of $58.1 million.