Do not change brands of generic drugs during treatment, warns Anvisa

The habit of choosing the most affordable generic drug, rather than a specific brand, is common among millions of Brazilians who want to save money.

However, the National Health Surveillance Agency (Anvisa) warns that replacing the manufacturer of generic and similar drugs during treatments is not advisable.

What are generic drugs?

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To understand why the regulatory agency for medicines do Brasil issues such guidance, it is essential to understand the approval process for generics and similar products.

Most drugs widely consumed in the country have already had their patents expired, allowing one or more laboratories to produce them as generics or similar.

To approve a new drug (reference), the developer must go through an extensive process of clinical studies that prove the safety and efficacy of the drug. After evaluation by Anvisa, registration takes place.

The laboratory holding the patent enjoys market exclusivity for 15 to 20 years. After this period, other companies can produce the drug formula.

Pharmaceutical companies interested in producing generics or similar products must demonstrate to Anvisa, through of new scientific studies, that its products are interchangeable with the drugs of reference.

Why switching generic drugs during treatment is not indicated?

“Interchangeability, that is, the safe replacement of the reference medicine by its generic, is proven by therapeutic equivalence tests, which include comparison in vitro, through pharmaceutical equivalence studies and in vivo, with the bioequivalence studies presented to the National Health Surveillance Agency", explains the Anvisa.

Losartan, a drug often prescribed for hypertension, is produced by 22 laboratories in Brazil, in generic and similar versions, which must not be switched during a treatment.

“Generic drugs cannot be considered interchangeable with similar ones, nor can generics be interchangeable between themselves, nor the similar ones can be considered interchangeable among themselves, because they didn't make this experimental demonstration", says the Anvisa.

The agency emphasizes that, due to the diversity of generics and similars available on the market, it would be impracticable to carry out interchangeability tests between all of them.

Despite sharing the active ingredient, generic and similar manufacturers use different raw materials and production and quality control methods. Differences in the technology used in production and in the excipients also exist.

These divergences can influence the absorption, metabolism or elimination of the drug in the body, affecting the efficacy and safety of the therapy.

Anvisa's recommendation is that patients observe signs and symptoms, monitor the effectiveness of the drug and report any changes to the doctor.