Does treatment with Clarityn (loratadine) and Depo-Medrol (methylprednisolone) in early pregnancy p

Fråga: Does treatment with Clarityn (loratadine) and Depo-Medrol (methylprednisolone) in early pregnancy pose any risk to the fetus? Background: A woman pregnant in week 6 was treated with an intramuscular injection of 40 mg methylprednisolone week 6+1 and with 10 mg loratadine daily week 6+1-3 due to suspected allergy.

Sammanfattning: There is no data supporting an increased risk for malformations due to loratadine intake during pregnancy. Long-term treatment with high doses of corticosteroids results in reduced weight of placenta and birth weight of the infant but there is no data indicating an increased risk for malformations due to a single intramuscular injection of methylprednisolone.

Svar: Questions concerning methylprednisolone and loratadine during pregnancy have previously been addressed in several drugline documents (1-9).

In summary, loratadine belongs to category B:3 in The Swedish Catalogue of Approved Medical Products meaning that teratogenic effects have been shown in animals. However, the importance of this in humans is unclear. Loratadine is marketed as an over the counter drug since 1992, and about 2 billion doses had been sold until the first half-year of 1996 (10). This means that a large number of fertile women must have been exposed by now. However, there are no reports on teratogenic effects of the drug. Personal communication with the manufacturer has not provided any new data (11). A prospective study on loratadine in early pregnancy has been performed (unpublished data, 12). Two hundred fifty-nine pregnancies with exposure during the first trimester compared to a control group have not shown any increased risk for malformations in the treatment group.

Methylprednisolone is classified as category C in The Swedish Catalogue of Approved Medical Products, meaning that the drug due to its pharmacological effects is assumed to affect the fetus without being directly teratogenic. It is known that a long period of exposure with high doses of corticosteroids results in a reduced weight of placenta and birth weight of the infant. Studies in animals have shown an increased risk for skeletal malformations, such as cleft palate. No teratogenic effects have been shown in humans. According to the manufacturer (13) there is no data indicating an increased risk for malformations due to a single intramuscular injection with a moderate dose of methylprednisolone in early pregnancy.

This case has also been discussed with an expert (12) who concludes that there is no data supporting any increased risk for malformations compared to a normal pregnancy due to the above mentioned drug intakes.

An updated search in Medline has not revealed any new information concerning teratogenic effects of methylprednisolone and loratadine.

In the files of the Swedish Adverse Drug Reactions Advisory Committee (14) there is no report on malformations after use of methylprednisolone. One case of eye and ear malformation has been reported after treatment with loratadine, which, however, has been judged as unlikely.