Home Original News Paroxetine (Paxil or Paxil CR) can more than triple major cardiac birth defects
Paroxetine (Paxil or Paxil CR) can more than triple major cardiac birth defects PDF Print E-mail
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Written by Roman Bystrianyk   
Friday, 29 December 2006 00:00

Paroxetine, known by the brand names Paxil or Paxil CR in the United States, is a selective serotonin reuptake inhibitor, or SSRI, antidepressant. Paroxetine was introduced in 1992 by GlaxoSmithKline and has become one of the most prescribed antidepressants on the market. In fact, paroxetine is the third most prescribed antidepressant in the United States and the most prescribed antidepressant in Canada. 

In late 2005 the FDA and Health Canada issued two warnings regarding first trimester exposure to paroxetine and the increased risk of cardiac malformation in newborns. A study in Reproductive Toxicology published in April 2006 showed a two-fold increased risk of cardiac malformations in women taken paroxetine during the first trimester. This conclusion agreed with earlier unpublished reports performed in 2005 by GlaxoSmithKline also showing a doubled risk of cardiac malformations. 

A new study published in Birth Defects Research Part B: Developmental and Reproductive Toxicology, examined in greater detail the association between exclusive first trimester exposure to paroxetine and the occurrence of any major congenital malformation, and more specifically, major cardiac malformations. The authors used a number of medical databases examining all pregnancies that occurred in Quebec between January 1997 and July 2003. 

Adjusting for a number of variables, as well as for second and third trimester exposure to antidepressants, paroxetine exposure during the first trimester or pregnancy compared with the use of other SSRI and non-SSRI antidepressants did not significantly raise the risk of congenital malformations. Although this showed no difference in birth defects it must be taken with the information found in a recent population-based cohort study that found the use of any SSRI antidepressant in the first trimester of pregnancy resulted in a 40% increase in birth defects and more specifically a 60% increased risk in cardiac abnormalities.

When the study authors examined a dose of paroxetine of greater than 25 mg (milligrams) they found a major increase in general birth and specifically cardiac defects. “Paroxetine was significantly associated with a two-fold increase in the risk of major congenital anomalies, and more specifically with a three-fold increase in the risk of major cardiac anomalies.” 

Again, this study compared paroxetine with other antidepressant drugs so the 200% increase in major congenital birth defects and 300% increase in cardiac malformations could reasonably be 240% and 360% if compared to those not taking any antidepressant medication. 

The authors conclude, “using a population based pregnancy registry, our study showed no increased risk of major congenital malformations, specifically major cardiac malformations, associated with the first trimester exposure to paroxetine. For the first time, however, a dose-response relationship between average daily dose of paroxetine utilization during the first trimester of pregnancy and occurrence of major congenital malformations, and major cardiac malformations, was found. Pregnant users of more than 25 mg/day of paroxetine were at a two-fold increased risk of having an infant with a major malformation, and at a three-fold increased risk of having an infant with a major cardiac malformation.”


Source: Birth Defects Research Part B: Developmental and Reproductive Toxicology, December 2006
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Last Updated on Wednesday, 09 September 2009 02:01