LA JOLLA PHARMACEUTICAL PRESENTS AT 10TH INTERNATIONAL CONGRESS ON ANTIPHOSPHOLIPID ANTIBODIES

SAN DIEGO, October 3, 2002 -- La Jolla Pharmaceutical Company (Nasdaq: LJPC) will discuss today the design and progress of its ongoing Phase I/II clinical trial of LJP 1082 for the treatment of antibody-mediated thrombosis at the 10th International Congress on Antiphospholipid Antibodies in Sicily. Keith Cockerill, Ph.D., Associate Director of Research, will present a talk entitled "Design and Clinical Development of a beta-2 GP1 B cell Toleragen® for the Treatment of Antiphospholipid Syndrome."

The Phase I/II double-blind, placebo-controlled, escalating single-dose study is designed to evaluate the safety of LJP 1082 and explore the impact of drug treatment on disease-causing antibodies. In the trial, five different groups, each consisting of four or five patients, were treated with a single dose of LJP 1082 ranging from 1 mg to 200 mg and then monitored for 30 days. One patient in each group received placebo. In order to participate in the trial, patients with antibody-mediated thrombosis were required to have elevated levels of antibodies to beta-2 glycoprotein 1, the target of the antibodies involved in the disease.

"Twenty-one patients have completed the trial. The final patient is scheduled to complete the study in mid-October," said Steven B. Engle, Chairman and CEO. LJP 1082 is designed to specifically prevent the production of disease-causing antibodies, while leaving the rest of the immune system fully functional and without the increased risk of bleeding episodes associated with existing anticoagulant therapy.

In a second presentation, Senior Research Scientist G. Michael Iverson, Ph.D. will discuss data confirming that disease-causing antibodies from patients with antibody-mediated thrombosis bind primarily to domain 1 of beta-2 GP1. The talk is entitled "The Orientation of beta 2-glycoprotein 1 on the Plate is Important for the Binding of Anti-B2-GP1 Autoantibodies by ELISA."

Antibody-Mediated Thrombosis (Antiphospholipid Syndrome)

Antibody-mediated thrombosis is an autoimmune disease characterized by the formation of blood clots that lead to stroke, heart attack, deep vein thrombosis and recurrent miscarriage. This disease affects an estimated one to two million people in the United States and Europe. Patients often experience their first thrombotic event in their 20s or 30s, and studies indicate they have twice the probability of a recurrence compared to individuals without disease-causing antibodies. Current treatments include anticoagulants, which are difficult to manage and can lead to side effects including life-threatening bleeding events. LJP 1082 is the first drug candidate specifically designed to treat the underlying cause of antibody-mediated thrombosis.

La Jolla Pharmaceutical Company is a biotechnology company leading the development of therapeutics for antibody-mediated autoimmune diseases afflicting several million people in the United States and Europe. The Company is conducting a Phase III trial of LJP 394 in patients with lupus kidney disease, a leading cause of sickness and death in these patients. The Company is also conducting a Phase I/II trial of 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 our Web site: http://www.ljpc.com. Patients interested in the Phase III lupus trial may call 1-888-30-LUPUS for information.

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. Our analyses of clinical results of 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 future analyses 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. Our blood test to measure the binding affinity for LJP 394 is experimental, has not been validated by independent laboratories, may require regulatory approval and may be necessary for the approval and the commercialization of LJP 394. 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. Even if results are promising, the U.S. Food and Drug Administration ("FDA") may require additional clinical trials. The Company's ability to develop and sell its products in the future may be affected by the intellectual property rights of third parties. Additional risk factors include the uncertainty of: obtaining required regulatory approvals; successfully marketing products; receiving future revenue from product sales or other sources such as collaborative relationships; future profitability; the need for additional financing; our dependence on patents and other proprietary rights; FDA approval of our manufacturing facilities; the increase in capacity of our manufacturing capabilities for possible commercialization; and our lack of marketing experience. 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 other reports and registration statements filed with the Securities and Exchange Commission from time to time, including the report on Form 10-K for the year ended December 31, 2001.