• Sodium oxybate (Xyrem®) is an orphan drug that has been available
since 2006. It is licensed for the treatment of narcolepsy with
cataplexy, a rare and debilitating condition that results in frequent,
uncontrolled, and short duration episodes of sleep leading to a range
of other symptoms such as disturbed night-time sleep and excessive
daytime sleepiness. Cataplexy is the loss of muscle tone and
frequently occurs with narcolepsy. It can cause patients to collapse
with resulting injuries. Patients with narcolepsy with cataplexy have
poorer quality of life and experience negative social effects.

• Sodium oxybate enables patients to achieve near-normal levels of
night-time sleep, resulting in reduced symptoms including cataplexy.
It has demonstrated efficacy against placebo in two short term
randomised studies with up to 12 month’s follow-up, and in a
comparison with the stimulant modafinil. The improvements are
dose-related and of uncertain practical importance. There is limited
evidence that sodium oxybate therapy has a positive impact on
functional aspects of quality of life.

• Sodium oxybate is associated with a relatively high frequency of
adverse effects, particularly nausea, headaches, dizziness, bedwetting,
and confusion, amongst others. It also appears to have
anorectic effects in a proportion of patients. However, despite these
effects, the majority of patients remain on treatment. The incidence
and severity of withdrawal effects appears to be small.

• Sodium oxybate is an expensive treatment. Using the mean dose
from clinical studies the cost is about £12,000 per patient per
annum. There are an estimated 221 diagnosed cases of narcolepsy
with cataplexy within NHS North East. Treating 10% of these at the
mean dose would cost about £336,000 per annum.

• Data indicates that in UK practice lower mean doses are used which
will reduce the cost proportionately. Sodium oxybate is unlikely to
satisfy conventional limits for cost-effectiveness if applied to all
eligible patients. It may be suitable for shared-care with provision in
primary care negating VAT.

• Sodium oxybate has abuse potential and is associated with a strict
administration regimen. It is not licensed nor has it been robustly
evaluated in paediatric (aged < 18 years) patients.