Morphine is no better than inactive placebo in preventing pain during procedures performed on preterm infants, according to new study findings.

This issue is important, the investigators explain, because pain from repeated procedures may permanently affect how these individuals process pain throughout their lives.

Dr. Ricardo Carbajal and his associates suggest in the medical journal Pediatrics that the lack of pain relief with morphine in preemies may be caused by the immaturity of morphine drug receptors in the body or by altered breakdown of the drug in the liver.

Although morphine is commonly used during routine procedures on preemies, previous studies of morphine use in this population have yielded mixed results.

For their own trial, Carbajal, from Hopital d’Enfants Armand Trousseau in Paris, and his team studied 42 premature infants who required a mechanical ventilator for breathing assistance. The infants were randomly selected to receive morphine or placebo during painful procedures, such as blood draws. Standard scoring systems were used to gauge pain.

As noted, the authors found no evidence that morphine was any better than placebo at controlling pain.

Morphine treatment in premature infants should be “limited to the presence of severe ongoing pain or clinical situations in which morphine provides short-term clinical benefits,” Carbajal and colleagues advise. Even then, they say, doctors should take advantage of other pain relief approaches.

SOURCE: Pediatrics, June 2005.