EXHIBIT 99.1

                 LA JOLLA PHARMACEUTICAL PROVIDES UPDATE ON NDA
                     FILING REGARDING ACCELERATED APPROVAL

                 CONFERENCE CALL SCHEDULED FOR 1:30 P.M. EASTERN

SAN DIEGO, JULY 24, 2003 - La Jolla Pharmaceutical Company (Nasdaq: LJPC)
announced today that, based on recent discussions with the United States Food
and Drug Administration (FDA), the Company may pursue an accelerated approval
for its lupus drug candidate, Riquent(TM), under the FDA's Subpart H regulation.
The FDA will make the determination of approvability and the conditions of the
approval after it has reviewed the Company's New Drug Application (NDA). As
previously announced, La Jolla Pharmaceutical plans to submit an NDA for Riquent
around the end of this year.

Under Subpart H, drugs in development for serious, life-threatening diseases
with an unmet medical need can be approved on an accelerated basis if the FDA
determines that the effect of the drug on a surrogate endpoint is reasonably
likely to predict clinical benefit and that a post-marketing clinical trial can
be successfully completed following drug approval which confirms the clinical
benefit. A post-marketing clinical trial may need to be initiated prior to
approval, but under Subpart H, such a trial would not need to be completed until
after approval. The Company is currently in discussions with the FDA about the
design and timing of a post-marketing clinical trial.

As previously announced, in the Company's Phase 3 and Phase 2/3 trials, patients
treated with Riquent had significantly reduced levels of antibodies to
double-stranded DNA (dsDNA) compared with patients treated with placebo. The
Company believes that data from its clinical trials and the relevant medical
literature would support the use of antibodies to dsDNA as a surrogate endpoint
that would be reasonably likely to predict clinical benefit.

"The outcome of our recent discussions with the FDA is an important step forward
for the Company," said Steve Engle, Chairman and CEO of La Jolla Pharmaceutical
Company. "Not only does Subpart H offer an alternate pathway for potential
approval of Riquent, but it also may enable an accelerated approval of Riquent,
allowing patients to gain access to Riquent while an additional post-marketing
study is ongoing."

Lupus is a chronic, life-threatening autoimmune disease afflicting about 1
million people in the United States and Europe. A significant number of lupus
patients develop kidney disease, a leading cause of morbidity and mortality in
lupus patients. The current standard of care for lupus kidney disease involves
treatment with corticosteroids and chemotherapy drugs that can cause severe side
effects including diabetes, hypertension and sterility, and may leave patients
vulnerable to opportunistic infections. Riquent is designed to specifically
prevent the production of antibodies responsible for lupus kidney disease
without suppressing the normal functions of the immune system.

The Company will host a conference call today, Thursday, July 24, 2003, at 1:30
p.m. Eastern Time. The dial in number is (800) 299-6183 for U.S. callers and
(617) 801-9713 for international callers. The call identification number is
98432801. A live audio




webcast of the conference call will be available through La Jolla
Pharmaceutical's Web site at www.ljpc.com.

The webcast will also be available to both institutional and individual
investors via CCBN's Investor Distribution Network. Individual investors can
listen to the call through CCBN's individual investor center at
www.companyboardroom.com or by visiting any of the investor sites in CCBN's
Individual Investor Network. Institutional investors can access the call via
CCBN's password-protected event management site, StreetEvents, at
www.streetevents.com.

A replay of the conference call can be accessed by dialing (888) 286-8010 (US)
or (617) 801-6888 (International). The passcode for the replay is 27190619. The
call will be available for approximately one week. A replay of the call will
also be available on the Company's website.

La Jolla Pharmaceutical Company is a biotechnology company developing
therapeutics for antibody-mediated autoimmune diseases 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.

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