Sildenafil Citrate, tablet, 20 mg, Revatio® November 2006
Public summary document for Sildenafil Citrate, tablet, 20 mg, Revatio®
Page last updated: 02 March 2007
Public Summary Document
Product: Sildenafil Citrate, tablet, 20 mg, Revatio®
Sponsor: Pfizer Australia Pty Ltd
Date of PBAC Consideration: November 2006
1. Purpose of Application
The submission sought a Section 100 (Highly Specialised Drug) listing for the treatment
of adult patients with primary pulmonary hypertension or pulmonary hypertension associated
with connective tissue disease (CTD), including scleroderma in patients categorised
as WHO (World Health Organisation) functional Class III.
Highly Specialised Drugs are medicines for the treatment of chronic conditions, which,
because of their clinical use or other special features, are restricted to supply
to public and private hospitals having access to appropriate specialist facilities.
2. Background
This drug had not previously been considered by the PBAC for this indication.
3. Registration Status
Sildenafil (Revatio) is registered to treat patients with pulmonary arterial hypertension
(PAH) classified as WHO functional classes II and III, to improve exercise capacity.
Efficacy has been shown in primary pulmonary hypertension and pulmonary hypertension
associated with connective tissue disease. The efficacy of sildenafil has not been
evaluated in patients currently on bosentan therapy.
Sildenafil (Viagra) is registered for the treatment of erectile dysfunction in adult
males.
4. Listing Requested and PBAC’s View
Section 100 (Highly Specialised Drugs Program)
Public and private hospital authority required
The requested Section 100 restriction for sildenafil was for the treatment of Class
III disease and was consistent with that of other PBS-subsidised PAH specific therapies
ie bosentan, iloprost and epoprostenol.
See Recommendation and Reasons for PBAC’s view.
5. Clinical Place for the Proposed Therapy
Primary, or unexplained, pulmonary arterial hypertension (PAH) is a rare lung disorder
which is characterized by sustained elevations of pulmonary artery pressure without
a demonstrable cause.
Sildenafil will provide clinicians with an alternative treatment for all currently
used agents in PAH class III patients.
6. Comparator
7. Clinical Trials
The submission presented three pivotal randomised, double-blind, multi-centre, parallel
group trials, one of sildenafil and two of bosentan, to provide an indirect comparison
of sildenafil to bosentan using placebo as the common comparator. The comparison was
made via an indirect meta-analysis of the primary outcome measure, the six minute
walking test (6MWT). Only TGA approved dosage arms (sildenafil, 20 mg tds; bosentan,
62.5 mg for 4 weeks then 125 mg maintenance dose) were included in the primary indirect
comparison.
These studies had been published at the time of submission, as follows:
|
Trial/First author |
Protocol title/Publication title |
Publication citation |
|---|---|---|
|
Sildenafil versus placebo |
||
|
SUPER-1: Trial |
Sildenafil citrate therapy for pulmonary arterial hypertension. |
New England Journal of Medicine, 353(20): 2148-2157 |
|
Bosentan versus placebo |
||
|
BREATHE-1: |
Bosentan therapy for pulmonary arterial hypertension. |
New England Journal of Medicine, 346(12): 896-903 |
|
Study 351 |
Effects of the dual endothelin-receptor antagonist bosentan in patients with pulmonary hypertension: a randomised placebo-controlled study. |
Lancet, 358(9288): 1119-23 |
|
Supplementary trial: Sildenafil vs bosentana |
||
|
SERAPH: |
Sildenafil versus Endothelin Receptor antagonist for Pulmonary Hypertension (SERAPH) study. |
American Journal of Respiratory and Critical Care Medicine, 171(11): 1292-1297 |
a: Not included as primary evidence because the sildenafil daily dose (50 mg tds) was higher than the TGA-approved daily dose.
8. Results of Trials
The results of the key comparative randomised trials showed that the distances walked
in 6 minutes for placebo were similar across the sildenafil versus placebo and the
bosentan versus placebo trials. Both sildenafil and bosentan resulted in a statistically
significant increase in distance walked in six minutes compared to placebo. However,
there was no statistically significant difference in the distance walked in 6 minutes
between sildenafil and bosentan.
The incidence of adverse events in the sildenafil and bosentan trials was comparable.
9. Clinical Claim
The submission claimed that sildenafil was no worse than bosentan in terms of effectiveness
and toxicity.
The PBAC agreed with the submission’s claim on the basis of the data presented.
10. Economic Analysis
The submission presented a preliminary economic evaluation using a cost-minimisation
approach. The resources included were drug costs, sildenafil and bosentan, and patient
monitoring.
Equi-effective doses in the context of cost-minimisation were sildenafil 20 mg tds
and bosentan 62.5 mg twice daily for 4 weeks then 125 mg twice daily as the maintenance
dose. This was based on the doses used in short term trials and is consistent with
TGA approved regimens.
The submission did not present an incremental cost effectiveness ratio but rather
a series of cost effectiveness ratios for the two drugs. The incremental cost per
metre gained in the 6 minute walk test was < $15,000.
A modelled economic evaluation was not presented.
11. Estimated PBS Usage and Financial Implications
12. Recommendation and Reasons
The PBAC recommended listing on a cost minimisation basis with bosentan for the treatment
of primary pulmonary hypertension or pulmonary hypertension associated with connective
tissue disease in patients categorised as WHO functional class III, at the price proposed
in the submission.
The PBAC agreed that on the basis of the data presented, sildenafil is no worse than
bosentan in terms of effectiveness and has similar toxicity. The equi-effective doses
are sildenafil 20 mg three times daily and bosentan 62.5 mg twice daily for 4 weeks
followed by a maintenance dose of 125 mg twice daily.
The PBAC recommended that the PBS restriction be the same as that for bosentan, taking
into account the differences in the TGA approved indications and dosage recommendations
of the two agents. As sildenafil has a relatively rapid onset of action, the sponsor
originally proposed that the duration of initial PBS-subsidised treatment with sildenafil
be limited to 3 months as opposed to 6 months for bosentan, and that patients be assessed
for response to treatment prior to the completion of this initial course of therapy.
The PBAC had no objection to this proposal. However, following the PBAC meeting, in
light of the additional burden of management that this restriction would require from
clinicians, patients and Medicare Australia, the sponsor indicated that it had re-considered
its position and agreed that the initial treatment period should be six months as
for bosentan.
The PBAC further agreed that patients accessing sildenafil for pulmonary hypertension
through the Special Access Scheme (SAS) at 1 November 2006 should be eligible to be
grandfathered onto PBS-subsidised therapy.
The PBAC recommended that the restriction specify that no increased maximum quantities
or repeats will be authorised consistent with the TGA approved maximum dosage and
recommended the 20 day safety net rule should not apply.
Recommendation
The PBS listing restriction can be found in the Schedule of Pharmaceutical Benefits
at www.pbs.gov.au.
13. Context for Decision
The PBAC helps decide whether and, if so, how medicines should be subsidised in Australia. It considers submissions in this context. A PBAC decision not to recommend listing or not to recommend changing a listing does not represent a final PBAC view about the merits of the medicine. A company can resubmit to the PBAC or seek independent review of the PBAC decision.
14. Sponsor’s Comment
The Sponsor welcomes the PBAC's recommendation for the listing of sildenafil (Revatio) on the PBS as it provides the specialist clinicians treating this comparatively rare and debilitating condition with an alternative therapy that acts on one of the three pathophysiological pathways associated with PAH that is not targeted by the other currently listed PAH therapies.
