Biological products have gained popularity in the recent years but according to a study published in the Journal of the American Medical Association, they seem to have more safety problems compared with chemical drugs.

Biological drugs, including enzymes, antibodies, growth factors, hormones and vaccines, are made from natural sources like human or animal tissues or microorganisms. These medicines are usually used to treat a variety of conditions including anemia, rheumatoid arthritis, hepatitis, and cancer.

However, Thijs Giezen of Utrecht University in the Netherlands and colleagues found that 1 in 4 biological products approved since 1995  (24 percent) had at least one safety-related regulatory action issued within 10 years of their approval. These drugs were subject of a total of 82 safety-related regulatory actions, although none was withdrawn. The regulatory action came about 4 years after the biological drug was approved, the study found. Also 11 percent of them were required to put a “black box” warning on the product.

Since January 195 to June 2008, US and European regulators approved 174 biological drugs. Between 2003 and 2006, biological products represented 24% of the new drug approvals in the US.

The problem with these drugs is that they contain components that are not easily recognized and categorized, says Dr. Phil B. Fontanarosa, executive deputy editor of JAMA. “The safety of these drugs is not always completely defined at the time of approval.” He presented the study at a news conference in Washington D.C.

The researchers said more work is needed before a biological drug is approved to understand its mode of action and thus its risks. Also, close surveillance of the products should continue after approval as well, with doctors being more aware of the fact that biological drugs are more dangerous than chemical ones.