Pregnant women should avoid taking a broad range of antidepressants and smoking-cessation medications because the drugs may cause their newborn babies to suffer serious side effects, ranging from respiratory problems to constant crying, Health Canada is warning.
In an advisory posted yesterday on its website, Health Canada said the danger is greatest when women take the drugs, in particular a newer class of antidepressants known as SSRIs, during the third trimester of pregnancy.
The regulatory agency said newborns whose mothers took the medications “can experience drug withdrawal symptoms or toxicity after delivery.”
The effects are wide-ranging, though the most common symptoms include respiratory problems, trouble eating, seizures, body rigidity, irritability, jitteriness and constant crying. In some cases, Health Canada warned, newborns may require tube feeding or breathing support, but said the symptoms appear to be reversible.
According to U.S. research, 10 to 15 per cent of pregnant women suffer from depression, but it is unclear how many are treated with antidepressants.
In the advisory, eight drugs were singled out as being of concern: bupropion, which is sold under the brand names Wellbutrin and Zyban, is prescribed both as an antidepressant and a smoking-cessation treatment. Both are products of GlaxoSmithKline and marketed in Canada by Biovail Corp.; citalopram, sold under the brand name Celexa, marketed by Forest Laboratories;fluoxetine, which is better known as Prozac, a product of Eli Lilly; fluvoxamine, sold under the brand name Luvox by Solvay; mirtazapine, sold under the brand name Remeron, marketed by Akzo Nobel; paroxetine, which is commonly known as Paxil, a product of GlaxoSmithKline; sertraline, sold under the brand name Zoloft, marketed by Pfizer; venlafaxine, best known as the drug Effexor, a product of Wyeth-Ayerst Laboratories.
Several of the drugs are selective serotonin reuptake inhibitors (SSRIs), a class of antidepressants that has been in the news a lot lately because of research suggesting they increase suicidal thoughts in children and adolescents, and reports that pharmaceutical companies withheld data showing the negative impact of these drugs.
In its advisory, Health Canada said: “If a woman is pregnant and is taking an SSRI, or other newer anti-depressant, she should discuss the risks and benefits of the various treatment options with her health-care professional. It is very important that patients do not stop taking these medications without first consulting with their doctor.”
The health regulator said it will also ask manufacturers to provide stronger warnings on the labels of drugs.
Wende Wood, a psychiatric pharmacist at the Centre for Addiction and Mental Health in Toronto, said the warning has to be taken in context. “There is a risk from these drugs, but we have to balance that against not being treated for depression during pregnancy and for post-partum depression.”
She said that women who are depressed eat poorly and tend to self-medicate with tobacco, alcohol and non-prescription drugs, all of which can cause far more severe damage to the fetus.
The new Health Canada advisory is similar to one issued in June by the U.S. Food and Drug Administration.
There, an expert panel studying the safety of SSRIs said it had received hundreds of reports of adverse effects in newborns. The scientists said they did not have enough data to understand precisely how the drugs affect newborns, but their use should be limited as a precautionary measure.
The expert panel cautioned, however, that depression itself in an expectant mother can have negative effects on the baby.
Since evidence arose about the effects of SSRIs on newborns, many physicians have had pregnant women slowly decrease the dose of antidepressant or stop completely to minimize drug withdrawal symptoms in the newborn baby.
Dr. Wood said that is not necessarily a sound approach. “We don’t know if this is dose related,” she said.
Earlier this year, the U.S. Food and Drug Administration ordered the manufacturers of 10 big-selling antidepressants to alter their labels to warn of a possible increase in suicidal thoughts and behaviours by people taking these prescription drugs.
Health Canada followed suit, issuing its own public health warning about seven SSRIs, excluding Prozac.