Effectiveness of Nifedipine for the Prevention of Preterm Labor: A Case Report

Abstract

We report the case of a 35-year-old pregnant woman treated with the calcium channel blocker, nifedipine, for maintenance tocolysis. She was hospitalized due to preterm labor at 21 weeks of gestation by her previous physician. A rash appeared following ritodrine hydrochloride administration for maintenance tocolysis. After changing to magnesium sulfate, a rash appeared again. As these rashes were suspected to have been induced by ritodrine hydrochloride and magnesium sulfate independently, consecutive treatment with these drugs was difficult. Therefore, she was transferred to our hospital for follow-up. At 28 weeks 6 days of gestation, treatment with nifedipine for maintenance tocolysis was started after receiving written informed consent, and the medication was approved by the institutional review board of our hospital. The attending pharmacist considered fetal/neonatal adverse effects of nifedipine, such as teratogenicity, fetotoxicity, and neonatal complications, as well as maternal side effects, such as headache, constipation, and excessive blood pressure drop. The pharmacist provided drug information about nifedipine to the attending physicians and nurses, and gave medication counseling to the patient. Following oral administration of 80 mg of nifedipine daily (20 mg every 6 hours), headache and constipation were evident but gradually improved. Neither excessive blood pressure drop nor exacerbated uterine contraction was observed throughout the period of nifedipine treatment. This medication was finished at 34 weeks 5 days of gestation and the patient was discharged at 36 weeks 2 days of gestation. She delivered a baby at 40 weeks 3 days of gestation. 緒 言 早産は， 正期産 （妊娠 37 週 0 日～妊娠 41 週 6 日） 以前の出産と定義されており，正期産と比較して 新生児合併症や新生児死亡などの周産期予後と密 接に関連することが知られている． 1-3） 早産児では， 呼吸窮迫症候群や脳室内出血，動脈管開存症など 児の長期予後に影響を与える重篤な合併症をきた す可能性が高くなることが報告されており， 1, 2） 実 際に，周産期死亡の約 75％は妊娠 37 週未満の早 産児が占めている． 3） 従って，早産の抑制は産科 管理の重要な課題の 1 つである． 切迫早産は妊娠 22 週以降～37 週未満に下腹痛 （ 10 分に 1 回以上の陣痛） ，性器出血，破水など の症状に加えて外側陣痛計で規則的な子宮収縮が あり，内診で子宮口の開大，頸管展退など Bishop score の進行が認められ，早産の危険性が高い状 態と定義されている．切迫早産の治療には一般的 に，子宮収縮抑制薬が投与される．本邦において 切迫早産に対して保険適応がある子宮収縮抑制薬