Decreased Plasma Lamotrigine (LTG) Levels Observed during Pregnancy
Abstract number :
1.282
Submission category :
Year :
2001
Submission ID :
3110
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
M. Li, MD, PhD, Neurology, University of Cincinnati, Cincinnati, OH; M.D. Privitera, MD, Neurology, University of Cincinnati, Cincinnati, OH; J.P. Szaflarski, MD, PhD, Neurology, University of Cincinnati, Cincinnati, OH; D.M. Ficker, MD, Neurology, Univer
RATIONALE: LTG has been used widely as an antiepileptic medication. Little information is known about changes of LTG levels during pregnancy. LTG is metabolized primarily by glucuronic acid conjugation in the liver; Metabolism is linear and time to steady state is about 24 hours as monotherapy. Three cases of decreased LTG levels during pregnancy were observed in past 4 years at our center.
METHODS: We reviewed charts on all patients seen in our epilepsy clinic who were on LTG in the past 4 years. We identified three patients who were pregnant between 1997 and 1999. Patient A is 21 years old with complex partial seizure (CPS) on LTG monotherapy. Patient B is 19 years old with CPS secondary to left insular gangliocytoma on a combination of LTG and gabapentin (GBP). Patient C is 33 years old on LTG monotherapy with simple partial seizure (SPS) and a single generalized tonic clonic (GTC) seizure prior to her current pregnancy. LTG levels were obtained monthly and dosage changes were made according to seizure control and clinician[scquote]s judgment about the level.
RESULTS: Patient A was on LTG at 400 mg/day with pre-pregnancy level 10.4 ug/ml. Patient B was on LTG 200 mg/day with pre-pregnancy level of 3.2 ug/ml. LTG was tapered to off prior to her pregnancy due to infrequent SPS. However, she had one GTC at 5 months gestation and LTG was restarted at 5 months. Patient C was on LTG at 400 mg/day and GBP at 2400 mg/day at the time of pregnancy. Her pre-pregnancy level of LTG was not obtained at 400 mg/day, and was 2.1 ug/ml previously on 300 mg/day. LTG levels and dosage changes during the pregnancy are shown in the table below. In all three patients, LTG levels decreased gradually during pregnancy and dosage was adjusted accordingly. All three patients give birth to normal babies without complication.
CONCLUSIONS: LTG levels decreased in 3 patients during pregnancy. Largest declines in the plasma levels/dosage ratio occurred in third trimester in all 3 patients. Maximum decreases in plasma levels ranged from 32-69%. Each case required increase in LTG dosage for adequate seizure control. The exact mechanism of decreased LTG level during pregnancy is currently unknown. Possible mechanism will be discussed.[table]
Support: NA