Effect of prenatal administration of doxycycline on growth rate of hind limb long bones in albino rat

Objective: To study the teratogenic risk of doxycycline treatment during pregnancy on long bone growth in hind limbs. Design: An observational study carried out on experimental albino rat. Place and Duration of Study: It was carried out in the Department of Anatomy, Basic Medical Sciences Institute (BMSI), Jinnah Postgraduate Medical Centre (JPMC), Karachi from June 1999 to May 2000. Subjects and Methods: Thirty-two healthy, 10-12 weeks old female albino rats obtained from the animal house of Elasic Medical Sciences Institute, JPMC, Karachi, were mated. The drug was given to 50% pregnant female albino rats in a dose of 8 mg/kg body weight intraperitoneally from 8th to 19th days of gestation, while remaining 50% received normal saline to serve as control. Intact embryos and pups were isolated by killing their mothers on days 15th-19th of gestation and on 1st postnatal day. All specimens were fixed in 80% ethanol, bulk stained with alizarin red and alcian blue and cleared in 4% KOH to reveal bony and cartilaginous elements. The right hind limbs were disarticulated from axial skeleton and observed under stereomicroscope. The total length of femur, tibia, fibula and metatarsal bones were measured and compared with those of control animals. Results: At the end of experimental period the drug receiving animals showed retardation in length of femur by 12.6%, in tibia by 14.06%, in fibula by 13.8% and in metatarsals 1-5 by 7.46, 7.96, 7.89, 7.96 and 7.82% respectively when compared with animals of control group. Conclusion: Treatment with doxycycline during pregnancy presents a risk of bone growth abnormality.