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Date: Oct 18 2010

Nektar Presents New Preclinical Data on NKTR-181 at Anesthesiology 2010
Nektar Presents New Preclinical Data on NKTR-181 at Anesthesiology 2010

Studies Demonstrate NKTR-181 Has Reduced Abuse Liability with Equivalent Analgesia to
Oxycodone in Preclinical Models of Abuse and Pain

San Carlos, Calif., October 17, 2010 – Nektar Therapeutics (Nasdaq: NKTR) today presented
new preclinical data demonstrating that NKTR-181, a mu-opioid analgesic with a novel
molecular structure, dramatically reduces abuse liability while providing analgesia comparable to
oxycodone and morphine. These data were presented during the poster session entitled "Chronic
and Cancer Pain” held today at the American Society of Anesthesiologists (ASA 2010) Annual
Meeting on October 17, 2010 in San Diego, CA.

NKTR-181 was uniquely designed to cross the blood-brain barrier at a substantially slower rate
than other opioid therapies. With a reduced rate of entry into the CNS, NKTR-181 has the
potential to eliminate not only the euphoria that underlies opioid abuse liability and dependence
but also the serious CNS-related side effects of respiratory depression and sedation. The unique
molecular design of the polymer drug conjugate also prevents conversion of NKTR-181 by the
user into a rapid-acting abusable form of an opioid. NKTR-181 is currently in IND-enabling
studies and Nektar plans to begin Phase 1 clinical studies in the first part of 2011.

"New therapeutics to manage chronic pain without the serious risks associated with existing
opioids are desperately needed,” said Lynn R. Webster, MD, Medical Director of Lifetree
Clinical Research and Pain Clinic and President, Utah Academy of Pain Medicine. "A novel
opioid therapy, such as NKTR-181, with low abuse potential and fewer CNS-related side effects
than existing opioids provides great promise for pain practitioners looking for safer, more
effective pain management.”


NKTR-181 Data Highlights from ASA 2010

In a preclinical in vivo model of pain, NKTR-181 showed comparable analgesic efficacy to both
oxycodone and morphine. In self-administration studies in non-human primates that are used to
predict abuse liability of compounds, NKTR-181 showed a marked reduction in selfadministration
of drug as compared to both oxycodone and morphine. Additionally, in a series
of in situ brain perfusion studies, NKTR-181 exhibited a significantly reduced rate of entry into
the CNS as compared to oxycodone.

These data were presented at Anesthesiology 2010: American Society of Anesthesiologists
Annual Meeting during the poster session entitled "Chronic and Cancer Pain”:

• Fishburn et al., "NKTR-181, a Novel Opioid Analgesic with Slow Entry into the CNS and
Markedly Reduced CNS Side Effects” (Abstract A509), October 17, 2010, 9:00 – 11:00
AM Pacific time, Room Hall B1-Area G.
The poster presentation can be found on Nektar’s website at www.nektar.com.


About Opioids and Pain Management

Pain is the most common symptom for which patients seek medical attention.1 According to the
American Pain Society, the prevalence of chronic pain in the United States is estimated to be
35.5% or 105 million people. Chronic pain costs more than $100 billion per year in direct
health-care expenditures and lost work time. Opioids are considered to be the most effective
therapeutic option for pain and have over $10 billion a year in sales in the U.S. alone.2,3
However, opioids cause significant problems for physicians and patients because of their serious
side effects such as respiratory depression and sedation, as well as the risks they pose for
addiction, abuse, misuse, and diversion. The U.S. Food and Drug Administration has cited
prescription opioid analgesics as being at the center of a major public health crisis of addiction,
misuse, abuse, overdose and death.4 A 2010 recent report from the Center for Disease Control
and Prevention (CDC) notes that emergency room visits tied to the abuse of prescription
painkillers is at an all-time high, having increased 111 percent over a five-year period.5


About NKTR-181

NKTR-181 is a novel mu-opioid analgesic investigational drug candidate created using Nektar’s
small molecule polymer conjugate technology. In preclinical studies, NKTR-181 exhibits a
reduced rate of entry into the central nervous system (CNS) providing effective pain relief with
fewer CNS-related side effects, such as euphoria, sedation and respiratory depression. The
unique molecular design of the polymer conjugate also prevents conversion of NKTR-181 into
free opioids or an abusable form of an opioid. As a result, NKTR-181 has the potential to be a
highly effective analgesic with a favorable safety profile and reduced potential for abuse, misuse
and diversion.