The main drug regulator of Europe found no new issues related to the safety of drugs after an investigation Roche Swiss drugmaker, which was tapped last year for the weak of drug safety.
The European Medicines Agency (EMA) launched an investigation into Roche in June 2012 after a routine inspection found that the court did not properly assess the tens of thousands of cases of possible adverse drug reactions.
The study includes 19 centrally authorized medicines, some of which were from cancer. Roche is the world's largest manufacturer of cancer drugs, and drugs for viral infections and inflammatory diseases.
Pharmaceutical companies need to assess the problems encountered by doctors and patients after taking their drugs and then pass on any serious cases of regulators. Roche inspection found many of these reports have not been properly evaluated by the company.
EMA initially put the potential number of unreported adverse reactions to 80,000, but that figure has since been revised down to about 23,000, a spokesman for Roche said.
A large number of unreported cases leads to the conclusion that there may be unforeseen safety issues with some of the drugs Roche, including the widely used brands, such as Avastin and Herceptin cancer, and Tamiflu tablets.
In the case, EMA said its careful analysis of drugs taken Roche has not identified any significant new security problems.
"The balance of benefits and risks of these drugs was not injured and there are no new recommendations for their use. Patients should continue to take these drugs, as previously noted, "the agency said in a statement.
Roche, however, could still face legal procedures breach the European authorities for failing to so-called "pharmacovigilance" obligations.
Basel Pharmaceuticals said it welcomed the conclusion of EMA review, adding that he has put in place corrective actions related to the collection, processing, evaluation and reporting of adverse event data.
Unusually extensive investigation of drugs Roche was called a routine inspection of the object Roche in the UK, which found that it was not properly evaluated thousands of reports related to company-sponsored patient support program, beginning in 1997.
These cases involved a considerable number of deaths that may or may not have been associated with medications.
Adverse drug reporting is designed to catch potential problems with medicines by setting a requirement for notification when a patient dies or suffers medical setbacks - even if it may be related to their underlying disease.
EMA - the equivalent of the U.S. Food and Drug Administration (FDA) - regularly pharmacovigilance inspections to make sure the pharmaceutical companies incidents properly.