Exhibit 99.1

LA JOLLA PHARMACEUTICAL DISCOVERS SMALL MOLECULE THAT PRODUCES POSITIVE RESULTS
                 IN AUTOIMMUNE DISEASE AND INFLAMMATION MODELS

SAN DIEGO, DECEMBER 2, 2003 -- La Jolla Pharmaceutical Company (Nasdaq: LJPC)
today announced the discovery of novel, orally-active small molecules for the
treatment of autoimmune diseases and acute and chronic inflammatory disorders.
Company scientists have generated highly selective inhibitors of SSAO
(semicarbazide-sensitive amine oxidase), an enzyme that has been implicated in
inflammatory responses in many tissues and organs. Preclinical studies in animal
models of multiple sclerosis, rheumatoid arthritis and acute inflammation have
shown that treatment with the Company's inhibitors both maintained function and
reduced disease activity compared with placebo treatment.

"We have discovered several families of potent, orally-active small molecule
inhibitors of SSAO that reduce disease in a variety of animal models," said
Matthew Linnik, Executive Vice President of Research and Chief Scientific
Officer of La Jolla Pharmaceutical Company. "The impact of these lead compounds
on animal models of multiple sclerosis and rheumatoid arthritis was similar to
that of methotrexate, a widely used anti-inflammatory agent. We are excited
about the potential to provide a novel approach to treating a number of
debilitating diseases."

SSAO, also known as vascular adhesion protein-1 or VAP-1, was recently
discovered to be a dual-function molecule with enzymatic and adhesion
activities. SSAO contributes to the adhesion of white blood cells to endothelial
cells and is greatly amplified in inflamed blood vessels. The enzyme also
contributes to the production of molecules that exacerbate inflammation.
Increases in the levels of plasma or membrane-associated SSAO have been reported
for many inflammation-associated diseases including rheumatoid arthritis,
inflammatory bowel disease, diabetes, atherosclerosis, and chronic heart
failure. In preclinical studies conducted by Company scientists, SSAO inhibitors
blocked both the enzymatic and adhesion functions of SSAO and were shown in
animal models to be potent inhibitors of disease activity. These results will be
presented at the 2nd International Inflammatory & Immune Diseases World Summit
on March 8-10, 2004 in Baltimore, MD.

La Jolla Pharmaceutical Company is a biotechnology company developing
therapeutics for antibody-mediated autoimmune diseases and inflammation
afflicting several million people in the United States and Europe. The Company
is developing Riquent(TM), formerly known as LJP 394, for the treatment of lupus
kidney disease, a leading cause of sickness and death in patients with lupus.
The Company is also developing LJP 1082 for the treatment of antibody-mediated
thrombosis, a condition in which patients suffer from recurrent stroke,
deep-vein thrombosis and other thrombotic events. The Company's common stock is
traded on The Nasdaq Stock Market under the symbol LJPC. For more information
about the Company, visit its Web site: http://www.ljpc.com.

Except for historical statements, this press release contains forward-looking
statements involving significant risks and uncertainties, and a number of
factors, both foreseen and



unforeseen, could cause actual results to differ materially from our current
expectations. Forward-looking statements include those which express a plan,
belief, expectation, estimation, anticipation, intent, contingency, future
development or similar expression. Although we plan to submit a New Drug
Application ("NDA") for Riquent(TM), there is no guarantee that regulatory
authorities will approve Riquent in a timely manner, or at all. Our analyses of
clinical results of Riquent, previously known as LJP 394, our drug candidate for
the treatment of systemic lupus erythematosus ("lupus"), and LJP 1082, our drug
candidate for the treatment of antibody-mediated thrombosis ("thrombosis"), are
ongoing and could result in a finding that these drug candidates are not
effective in large patient populations, do not provide a meaningful clinical
benefit, or may reveal a potential safety issue requiring us to develop new
candidates. The analysis of the data from our Phase 3 trial of Riquent has shown
that the trial did not reach statistical significance with respect to its
primary endpoint, time to renal flare. Although we plan to submit an NDA for
Riquent, the results from our clinical trials of Riquent may not ultimately be
sufficient to obtain regulatory clearance to market Riquent either in the U.S.
or Europe, and we may be required to conduct additional clinical studies to
demonstrate the safety and efficacy of Riquent to obtain marketing approval.
There is no guarantee, however, that we will have the necessary resources to
complete any additional trial, that we will elect to conduct an additional
trial, or that any additional trial will sufficiently demonstrate the safety and
efficacy of Riquent. Our blood test to measure the binding affinity for Riquent
is experimental, has not been validated by independent laboratories, may require
regulatory approval, and will likely be necessary for the approval and the
commercialization of Riquent. Our other potential drug candidates are at earlier
stages of development and involve comparable risks. Analysis of our clinical
trials could have negative or inconclusive results. Any positive results
observed to date may not be indicative of future results. In any event,
regulatory authorities may require additional clinical trials, or may not
approve our drugs. Our ability to develop and sell our products in the future
may be affected by the intellectual property rights of third parties. Additional
risk factors include the uncertainty and timing of: obtaining required
regulatory approvals, including delays associated with any approvals that we may
obtain; the clear need for additional financing; FDA approval of our
manufacturing facilities and processes; the increase in capacity of our
manufacturing capabilities for possible commercialization; successfully
marketing and





selling our products; our lack of manufacturing, marketing, and sales
experience; generating future revenue from product sales or other sources such
as collaborative relationships; future profitability; and our dependence on
patents and other proprietary rights. Readers are cautioned to not place undue
reliance upon forward-looking statements, which speak only as of the date
hereof, and we undertake no obligation to update forward-looking statements to
reflect events or circumstances occurring after the date hereof. Interested
parties are urged to review the risks described in our Annual Report on Form
10-K for the year ended December 31, 2002, and in other reports and registration
statements that we file with the Securities and Exchange Commission from time to
time.

                                       ###