Going to any pharmacy and asking for a medicine by the name of the active substance, choosing the cheapest one, has already become a routine for millions of Brazilians. Few people always buy the same brand of medicine.

Anvisa (National Health Surveillance Agency) states that you should not change the manufacturer of generics and similar drugs during treatment. But to understand why the regulatory body makes such recommendations, it is necessary to know how the approval process for generics and similar drugs works. Information taken from R7.

Most of the medicines consumed in the country are patent expired and one or more laboratories may manufacture them in the form of generic or similar products. Photo: Arquivo/Agência Brasil

A large proportion of the country’s most consumed medicines have already had their patents expired, meaning that one or more laboratories may be producing them in generic or similar forms.

In order to approve a new drug (reference), the developer must go through a long and expensive plan of clinical trials proving the safety and effectiveness of this drug. The results are forwarded to Anvisa, which delays registration.

The laboratory holding this patent has an exclusive right in the market for a period of 15 to 20 years. After this period, the drug formula is transferred to companies interested in its production.

A pharmaceutical company that wants to produce a generic or similar product will need to demonstrate to Anvisa through new scientific studies that its product is interchangeable with the product of the company holding the patent for the first drug developed for this disease, i.e. called reference medicine.

“Interchangeability, i.e. the safe substitution of a generic drug for a reference drug, is ensured by therapeutic equivalence trials, including comparisons in vitro, through pharmaceutical equivalence studies and in vivo, with bioequivalence studies submitted to the National Health Inspection Agency,” the regulator explains on its web site. site. The same goes for peers.

The more medicines available, the more competition and prices fall.

Losartan, for example, one of the most commonly prescribed drugs for people with hypertension, is produced by 22 laboratories in the country, most of them in generic and similar versions that should not be changed during treatment.

“Generic drugs cannot be considered interchangeable with similar drugs, just as generic drugs cannot be interchanged with each other, nor can similar drugs be considered interchangeable with each other, because they did not conduct this experimental demonstration,” Anvis said in a note. sent by R7. .

Anvisa highlights the impossibility of testing generics

Anvisa notes that since there are several generics and similar drugs on the market, it is not possible to test the interchangeability of one with another, as there are hundreds of possibilities.

Although drugs have the same active ingredient, generic and similar manufacturers have different raw material suppliers, and production and quality control processes may also differ, in addition to differences in the technology used in production and in excipients (substances that do not have a pharmacological effect ). , but is necessary for the manufacture, stability and administration of the drug).

These differences may affect the absorption, metabolism or excretion of the drug from the body, which may lead to a change in the effectiveness and safety of therapy.

For example, therapies that involve the use of biological agents (derived from living organisms) may be more sensitive to exchange, notes clinical pharmacist Daniani Baldani da Costa Wilson of BP – A Beneficência Portuguesa de São Paulo.

“In the case of biological or biosimilar medicinal products in which the product is a process, despite the same indications, due to the fact that the manufacturing process is different, it is not recommended to interchange, since each patient may react differently.”

Patients undergoing hormone replacement therapy, as well as patients with hypothyroidism and taking levothyroxine, should be aware of this, explains endocrinologist Rodrigo de Oliveira Moreira, director of the diabetes department at SBEM (Brazilian Society of Endocrinology and Metabolism).

“In theory, the conversation about hormones, especially thyroid hormones, is that the dose of thyroid hormones is measured in micrograms, not milligrams. […] When going from one generic to another and from one similar to another, even knowing that the differences are small, when we are talking about micrograms, these differences can be significant.”

The expert gives another, even more common example, in the case of women.

“You sometimes have similar contraceptives, with the same amount of the hormone, also in very low doses, in micrograms. If you decide to switch from one to the other, you cannot say that you have the same dose of contraceptive, the same dose of the hormone. We also do not recommend such an exchange, or when you make an exchange, you advise you to wait at least two months to make sure that this dose is sufficient.

Patients undergoing psychiatric treatment are also generally advised to always buy drugs from the same lab and brand (if they are similar) in order to keep the blood levels of a certain active ingredient unchanged.

However, there are times when doctors advise patients to buy reference (more expensive) drugs, and this topic divides the opinions among the categories.

Professionals heard in the report privately say that this type of prescription does not make sense, since generics and similar drugs are approved by Anvisa as a cheaper alternative.

The Pharmaceutical Market Statistical Yearbook published by SCMED (Executive Secretariat of the Chamber of Medicines Market Regulation) at the beginning of the month shows that 70% of all drugs consumed in Brazil are generic (41%) or similar (41%). 29%).

The lower price is usually the reason why people choose generics and the like.

There is also an issue of availability, as it is not always possible to find the same medicine.

What to do if you cannot continue treatment with the same manufacturers and brands?

“It is recommended that the patient be aware of the signs and symptoms of treatment for the disease. If the medicine is having the expected effect, if the patient has noticed any symptoms that he has not experienced before, and report any phenomena that he noticed. In addition, it is extremely important to continue medical supervision,” Daniani directs.