The US pharmaceutical group Pfizer is known globally for its anti-impotence pill, Viagra.

In the United States alone, doctors have written more than 14 million prescriptions for the drug, making it available to some five million American men since Viagra's introduction in April 1998.

With revenues from drug sales of $14.8 billion last year, Pfizer is the seventh-largest manufacturer of pharmaceutical products, and is also active in the market for animal healthcare.

Total revenues in 1999 were $16.204 billion, which yielded a profit of $3.384 billion. The budget for research and development this year is around $3.2 billion.

Besides Viagra, Pfizer makes Norvasc, a medication for hypertension, Zoloft, an anti-depressant, Zithromax, an anti-biotic, and Zyrtec, an anti-allergy treatment.

In conjunction with WarnerLambert, Pfizer will market Lipitor, an anti-cholesterol medication.