Orexo reports successful completion of OX51 phase II dose-finding study in prevention of procedure-induced pain

Uppsala, Sweden – August 28, 2013 – Orexo today announced the successful
completion of a dose finding study for OX51 in patients undergoing prostate
biopsy, as the study met its primary end-point of analgesic efficacy. The
placebo controlled study, which tested sublingual administration of 3 different
doses of OX51 and placebo, demonstrated a statistically significant dose
response with respect to maximal pain experience during the biopsy procedure.
Treatment with OX51 was safe and well-tolerated in all dose groups and no
effects on local tolerability in any dose group were observed. In addition OX51
showed no effect on quantitative scales for assessment of sedation and
drowsiness compared to placebo.

OX51 is a novel sublingual formulation comprising alfentanil, which has been
developed to meet the fast growing demand for efficient pain management during
short-term surgical and invasive diagnostic procedures. The quick onset, absence
of sedation and drowsiness, short duration, rapid offset and convenient
administration of OX51 makes it suitable for prevention of pain for a multitude
of surgical and diagnostic procedures.

The market for short-term surgical and diagnostic procedures is large and
growing with over 130 million procedures performed annually in the US and EU.
This growth is driven by both improvement in technology, and a result of an
increasing cost control, which propels a shift in such procedures from an in
-patient/hospital setting towards an outpatient setting. This shift has created
a major need for improving efficient pain management during the short-term
surgical and diagnostic procedures without the full access to all resources
otherwise found in a hospital.

“OX51 is yet another innovation from Orexo meeting a fast growing need from
patients and health care providers. We estimate that the commercial potential of
OX51 in short-term surgical and diagnostic procedures not requiring full
anesthesia is substantial. With these positive results we will now consult the
regulatory agencies to decide the best path forward for OX51, while ensuring
that the organization remains focused on the launch of Zubsolv for opioid
dependence in 2013, ”said Nikolaj Sørensen, President and CEO.

For further information, please contact:
Nikolaj Sørensen, President and CEO
Tel: + 46-703 50 78 88, Email: nikolaj.sorensen@orexo.com

About Orexo
Orexo AB is an emerging specialty pharma company with commercial operations in
the United States and R&D in Sweden developing improved treatments using
proprietary drug delivery technology. Orexo’s expertise is within the area of
reformulation technologies and especially sublingual formulations. The company
has a portfolio of revenue generating US and EU approved products currently
marketed under licence and a pipeline of several reformulations of approved
compounds for areas of unmet medical need. Orexo also has collaboration projects
with several international pharma companies. Orexo, with its headquarters in
Sweden, is listed on NASDAQ-OMX. The largest shareholders are Novo A/S and
HealthCap.

About OX51
OX51 is the first oral tablet formulation comprising alfentanil, which is being
developed for the prevention of acute and intense pain episodes in conjunction
with care-related diagnostic or therapeutic procedures. OX51 product
characteristics are very attractive for pain treatment during shorter procedures
according to market research among physicians and payers. The annual peak sales
potential is estimated at around MUSD 250.

About Prostate Biopsy
There are more than two million procedures of prostate biopsies performed
annually in Europe and the US. Most of these procedures are performed in an
outpatient setting. The diagnostic biopsy procedure is very standardized and
normally involves use of local injection analgesia and use of anesthetic cream,
but the resulting pain management is often inadequate and the procedure is often
painful.

About the OX51-002 Dose-Finding Study
This is a double-blind, randomized, placebo controlled study in 180 patients in
17 selected sites in 4 different Europe countries undergoing elective prostate
biopsy. The primary objective of this study is to evaluate the analgesic
efficacy of OX51 in 3 different doses compared to placebo during the procedure
in the chosen population.

For information about Orexo AB, please visit www.orexo.com.

Orexo is required under the Financial Instruments Trading Act to make the
information in this press release public. The information was submitted for
publication at 10:30 am CET on August 28, 2013.