Viagra 'ban' faces court challenge.
Manufacturer Pfizer is seeking a judicial review of Health Secretary Mr Frank Dobson's advice to doctors, when the drug was first licensed in the UK in September last year, that they should not prescribe it.
Pfizer claims Mr Dobson's decision was "unprecedented and discriminatory" because he did not place the drug on any of the three prescription schedules normally used for licensed drugs.
Drugs are either given an FP10 rating, which allows doctors to issue NHS prescriptions for anyone in clinical need, or placed on Schedule 10, which is effectively a blacklist for NHS prescriptions but allows private prescriptions.
Drugs can also be placed on Schedule 11, which allows the Health Secretary to specify certain criteria for NHS prescriptions.
When Viagra was given a UK licence, Mr Dobson did not use any of these three options, but instead sent doctors a Health Service circular telling them not to issue NHS prescriptions for the drug.
NHS chiefs fear huge demand for the drug could lead to prescription bills of up to pounds 50 million a year.
In January Mr Dobson proposed placing Viagra on Schedule 11, allowing only men with impotence caused by certain conditions to obtain NHS prescriptions. The British Medical Association told its members to defy Mr Dobson's advice and prescribe Viagra to any patient in clinical need.
The Health Secretary is now considering his final decision after the end last month of a consultation period over the proposals.
Any High Court ruling would not affect the prescribing of Viagra, which became the fastest-selling drug of all time when it was launched last year.
But Pfizer said it was challenging Mr Dobson's decision as "a point of principle".
A Department of Health spokeswoman refused to comment on Pfizer's legal challenge, which is to be heard in the High Court on May 10.
She said: "A decision is expected on Viagra shortly."