Ercros' pharmaceutical division's headquarters and production centre

The Aranjuez factory, a pioneer in the manufacture of antibiotics in Spain

The factory in Aranjuez (Madrid) is part of the pharmaceuticals division of Ercros and started its activity in 1951, becoming the first Spanish company to manufacture penicillin.

Today, this factory is dedicated to the production and sale of generic active pharmaceutical ingredients (APIs), mainly in the field of antibiotics. It is also active in the anti-ulcer, antihypertensive and antifungal segments, and in customised APIs and intermediates, known as contract manufacturing.

It is the world's second largest producer of fusidic acid and the third largest producer of fosfomycin. It exports virtually all of its production mainly to the EU, the US, the Middle East and North Africa.

The plant has three multi-purpose synthesis and fermentation plants, a sterile product production and blending plant, and a laboratory and R&D centre. The factory's overall production capacity is around 430,000 kg/year.

It employs more than 200 people.

Main street of the Aranjuez factory
Multi-purpose synthesis plant at the Aranjuez factory
Fermenters at the Aranjuez factory
Industrial fermentation towers at the Aranjuez factory
Night view of the Aranjuez factory
Night view of the multi-purpose synthesis plant and the solvent warehouse
Financial year 2022

In figures

The key figures of the Aranjuez factory



430,000 kg

Annual production capacity




Company manufacturing antibiotics in Spain

A bit of history

Instalaciones de la fábrica de Aranjuez en 1949

Compañía Española de Penicilicilina y Antibióticos (Cepa) in collaboration with the American company Merck & Co. Inc. wins a tender called by the Spanish government to develop a national antibiotics industry and becomes the first company to manufacture penicillin in Spain.

Laboratorio de la fábrica de Aranjuez en 1951

Inauguration of the Aranjuez factory, under the ownership of Cepa, with the most advanced equipment and processes. Its production capacity is 1.5 million vials of crystallised sodium penicillin per month.

Interior de una planta de la fábrica de Aranjuez en 1952

After several expansions of its facilities, the initial production of penicillin is doubled to meet the needs of the Spanish market.

Laboratorio de la fábrica de Aranjuez en 1968

Cepa, together with Merck, is developing a new antibiotic, fosfomycin, a market in which the Aranjuez factory will be one of the world leaders.

Folleto comercial de CEPA

Start of industrial-scale production of fosfomycin and, two years later, of a new antibiotic, erythromycin.

Construcción de fermentadores de la fábrica de Aranjuez en 1975

Cepa is acquired by Unión Explosivos Río Tinto, S.A. (ERT), the predecessor of Ercros.

Pilot plant at the Aranjuez factory in 1990

As a result of the merger of ERT and S.A. Cros to form Ercros, Cepa is split into two companies. One of them, Fermentaciones y Síntesis Españolas, S.A. (Fyse), retains the API manufacturing and the Aranjuez factory facilities and joins Ercros.

Laboratorio de la fábrica de Aranjuez

Industrial-scale production of the erythromycin derivatives, azithromycin and clarithromycin, begins.

Fermentation plant in Aranjuez

Commercialisation of fusidic acid begins.

Lateral de la planta de síntesis de la fábrica de Aranjuez

A new multi-purpose plant is commissioned to manufacture synthesis products. This considerably increases the centre's production volume.

Bidones de fosfomicina trometramol

Industrial production of fosfomycin trometamol begins.

Persona trabajando en la planta estéril de la fábrica de Aranjuez

Inauguration of a sterile product mixing and packaging plant.

Planta de productos estériles de Aranjuez

Expansion of the fermentation capacity and the synthetic products plant. A new sterile products plant is commissioned to replace the existing one.

Certificates of the Aranjuez factory

The distinctive marks that endorse this factory's commitment to sustainability.

Contact the factory

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Paseo del Deleite, s/n
28300 Aranjuez (Madrid)
Tel: +34 918 090 340