Positive Outcome of Drug-Drug Interaction Trial With Intravenous Iclaprim

Arpida Ltd (SWX: ARPN) announced today the results of a Phase I trial investigating the possible interaction between intravenous iclaprim and warfarin. Warfarin is widely used for the prophylaxis of thrombosis and embolism and its dosing needs to be well-controlled.The drug-drug interaction study comprised 24 healthy volunteers and was performed in Germany. Dosing of warfarin with and without pre- and co-administration of iclaprim (1.6 mg/kg infused over 60 minutes) was investigated.

Administration of intravenous iclaprim at this supra-therapeutic dose was assessed to be safe for clinical applications. It had no significant effect on the pharmakonetics and pharmacodynamics of warfarin. Moreover, the trial results again confirm the good safety and tolerability profile of iclaprim.

Dr Paul Hadvary, Head of Development of Arpida Ltd., commented: "The results of this Phase I study are very positive, showing that iclaprim has no significant effect on the pharmacokinetics of warfarin, which is widely used in the targeted patient population. The results expand the experience gathered in an earlier Phase I study in which the interaction between ketaconazole and iclaprim was investigated. In summary, iclaprim's drug-drug interaction profile looks favourable. This is of great importance as iclaprim is expected to be administered to patients with significant co-morbidities and receiving several other medications. These Phase I data add substantial weight to the NDA package that we intend to file shortly with the U.S. Food and Drug Administration for intravenous iclaprim in its first indication: complicated Skin and Skins Structure Infections (cSSSI)."

About Arpida Ltd.

Arpida (SWX: ARPN) is a biopharmaceutical company with research facilities near Basel, Switzerland and in the USA. It focuses on the discovery and development of novel drugs that seek to overcome the growing problem of microbial resistance. The most advanced compounds include an antibacterial close to NDA-filing and an antifungal in Phase III.

Arpida's leading product candidate is intravenous iclaprim, a potent, pathogen-focused, late-stage antibiotic that targets severe infections requiring hospital treatment, including those caused by methicillin-resistant Staphylococcus aureus (MRSA). The US Food and Drug Administration has granted fast track status to intravenous iclaprim. In March 2007, Arpida completed patient enrolment in the second pivotal Phase III trial in complicated skin and skin structure infections. The top-line data of the second trial were reported in July 2007. An NDA filing is expected to take place in the second half of 2007.

In June 2007, Arpida announced that it has received approval from the US FDA to initiate Phase II trials with intravenous iclaprim in the treatment of patients with hospital-acquired pneumonia (HAP), ventilator-associated pneumonia (VAP) or healthcare associated pneumonia (HCAP).

An oral formulation of iclaprim has successfully completed three Phase I trials: an ADME study (absorption, distribution, metabolism and excretion) with radiolabelled compound, a Phase I bioavailability trial with a solution and one with a capsule formulation. Iclaprim could be offered not only as an intravenous therapy for hospital use in acute situations, but also as an oral formulation, allowing early patient discharge followed by outpatient treatment. This switch should be a valuable instrument in reducing healthcare costs and enhancing patient comfort.

Arpida's fourth most advanced antibiotic programme, AR-709, targets upper and lower respiratory tract infections acquired in the community setting. AR-709 exhibited potent activity against a large panel of pneumococcal clinical isolates including those resistant to currently used drugs. Promising results of "first-in-man" studies with AR-709 were published in March 2007.

An additional compound, AR-2474, has achieved in vivo proof of concept. AR-2474 has been shown to be highly effective in eradicating pathogens in preclinical models of skin infection and nasal carriage.

Apart from the antibiotic programmes, Arpida has an innovative antifungal therapy (TLT) which is about to enter Phase III clinical trials in Europe, targeting onychomycosis.

Moreover, the company has several other leads in optimisation and additional discovery programmes derived from its own discovery platform at various research stages.

This press release contains specific forward-looking statements, e.g. statements including terms like believe, assume, expect or similar expressions. Such forward-looking statements are subject to known and unknown risks, uncertainties and other factors which may result in a substantial divergence between the actual results, financial situation, development or performance of the company and those explicitly or implicitly presumed in these statements. Against the background of these uncertainties readers should not place undue reliance on forward-looking statements. The company assumes no responsibility to update forward-looking statements or to adapt them to future events or developments.

Arpida contacts:

Dr Khalid Islam, President and CEOTel: +41-61-417-96-60

Harry Welten, MBA, CFO and Senior Vice President Tel: +41-61-417-96-65

Paul Verbraeken, Head of Corporate Communications Tel: +41-61-417-96-83