A charity is calling on the health watchdog to revise its "cruel" restrictions on the use of a prostate cancer drug.

Prostate Cancer UK said the the National Institute for Health and Care Excellence (Nice) should reverse its decision regarding enzalutamide, which is a life-extending drug for men with advanced disease.

In January, Nice, which vets the cost effectiveness of NHS treatments, published draft guidance saying men should not qualify for the medicine if they have previously been treated with another prostate cancer drug, abiraterone.

It said the drug, also known as Xtandi, should only be considered if the cancer has advanced during or after chemotherapy.

The restrictions regarding abiraterone were not in previous guidance - prompting campaigners to say Nice had performed a U-turn.

Patients in Scotland are already receiving the drug following approval by the Scottish Medicines Consortium (SMC).

In England, enzalutamide is on the cancer drugs fund list, which means patients can access it if their doctor requests it. However, the cancer drugs fund list is only intended for use before Nice publishes final guidance on a drug.

Owen Sharp, chief executive of Prostate Cancer UK, said Nice should use its committee meeting today to review its decision.

He said: "These rigid and nonsensical restrictions are throwing many families into despair, creating unnecessary anguish at the most stressful time of their lives.

"There can be few injustices as raw as someone with cancer at the end of their life being told that a breakthrough drug which could give them extra time will be snatched away from them based on a technicality.

"Is this the kind of 'care' Nice was set up to broker? The weight of support for our campaign suggests many disagree.

"Every hour one man dies of prostate cancer. It's high time Nice did the right thing by men and allowed them the unfettered access to this drug - just like men in Scotland."

Some 7,000 people have signed a petition urging Nice to reconsider its decision.

Data published last year showed that enzalutamide, which costs around £2,500 a month, can extend the lives of patients by almost five months.

Seven out of 10 of the men in the Phase III Affirm trial taking enzalutamide were still alive after one year.

The drug, previously known as MDV3100, blocks molecular signals that allow the male hormone testosterone to fuel prostate cancer.

Jackie Fitchett's husband, Ian, has no more options on the NHS.

She said: "My husband's prostate cancer has had a devastating effect on our lives and our family - it is a massive strain for all of us.

"Now, knowing that there is a successful licensed drug available but which we simply cannot access because he has had another treatment, seems very very unfair and cruel.

"It feels like they are putting a price on someone's life. We are actively searching around for other possibilities, which we will be selling our possessions to fund, but it is very stressful.

"My husband is dying and could be given extra time with this drug that could mean he was able to see our grandson's birthday or his 86-year-old dad's birthday.

"What has happened to the NHS that will help us when we are sick and at our most vulnerable? All we want to be doing is enjoying our precious time together. It seems that when you get towards the end of treatment, the situation becomes extremely cruel and merely comes down to how much keeping you alive will cost the NHS."

David Neal, professor of surgical oncology at the University of Cambridge, said: "Nice's decision that men with advanced prostate cancer should not be given enzalutamide if they have previously received abiraterone is not, in my view, based on good evidence that this approach lacks effectiveness.

"The mechanism of action of enzalutamide (it blocks the androgen receptor) is quite different from that of abiraterone (it blocks the synthesis of androgens).

"This decision of Nice will place doctors treating these men in a position of difficulty. They are therefore more likely to start with enzalutamide as first line treatment of hormone relapsed prostate cancer, which may not turn out to be the most cost-effective approach as abiraterone comes off patent."

A Nice spokeswoman said: "The preliminary recommendations were issued for consultation earlier this year.

"Consultees, including the manufacturer, healthcare professionals and members of the public were able to comment on the draft guidance.

"Comments and any additional data received during this consultation will be fully considered by the Committee and following this meeting the next draft guidance will be issued."

Nice said that in the trial data provided by the manufacturer of enzalutamide, none of the patients had received previous treatment with abiraterone.

Therefore the committee was not "able to draw any conclusions about the effectiveness of enzalutamide after previous abiraterone treatment".

Nice said it would welcome any additional data from the manufacturer.