A Comparative Study between the Efficacy of Ritodrine Hydrochloride Versus Nitroglycerin Patch as a Short Term Tocolysis

Abstract
Background: Preterm birth continues to be a problem for obstetricians. Preterm birth complicates 8-10% of birth. Although the causes of preterm labour are not well understood, the burden of preterm birth is clear. The majority of neonatal deaths and over one third of infant deaths are linked to preterm birth. Methods to detect preterm labour at early stage include ultrasound examination of cervix and detection of biochemical markers of preterm labour in blood, saliva and cervicovaginal secretion. Given the methods to predict and prevent preterm birth are imperfect, attention focuses on the treatment of women admitted with preterm labour.
Aim of the Work: The aim of the study to compare the safety and efficacy of transdermal nitroglycerine patch versus ritodrine hydrochloride in treatment preterm labour.
Patients and Methods: This retrospective study was in-cluded 50 cases of threatened preterm labour attending the Obstetrics and Gynecology Department of Tanta University Hospital who were involved in this study. Woman were randomly divided in this retrospective study into two groups: Group 1: Included twenty five (25) patient, they received B-sympathomimetc ritodrine (yutopar). Ritodrine was giving in dose of: 150mg in 500ml saline infusion starting dose is 0.05mg/min this to be increased 0.05mg/min every 10-15 minutes (1ml contain 0.3mg and 1ml about 16 drops so 0.05mg about 3 drops) until a dose that provide tocolytic effect is reached or maternal tachycardia above 130 beats/minute occur. Group 2: Included twenty five (25) patients treated with 10mg nitrodermal patch directly applied on the abdominal skin.
Inclusion Criteria: Pregnant woman in the age of 20-35 years, gestational age between 28-34 weeks, body mass index (25-30), singleton pregnancy, uterine contraction 2 per 10 minutes or 4 per 20 minutes, cervical dilatation 3 centimeters, effacement up to 80%, intact membranes and primigravida or multigravida.
Exclusion Criteria: Fetal problems: Fetal congenital anomalies, fetal growth restriction and fetal distress. Maternal problems: "Medical problems": Chronic hypertension, chronic renal disease, cardiac disease, diabetes mellitus, contraindi-cation to beta agonists, non-steroidal anti-inflammatory drugs and other tocolytics, cigarette smoker, anemia (HB less than 10mg/dl), thyroid disorders, maternal tachycardia ."Obstetric problems": Preeclampsia, polyhydraminos and oligohydrami-nos, ante-partum hemorrhage and rupture of membranes and Chorioamnionitis. All patients were subjected to thorough history taking with special emphasis on gestational age (in weeks), history of medical disease) and clinical examination regarding blood pressure and body mass index. Obstetrical abdominal ultrasound was done for gestational age (BPD, AC, FL), amniotic fluid, viability. Routine investigations as fasting blood sugar blood group and Rh factor, blood urea, creatinine, haemoglobin concentration and analysis of urine albumin, sugar, microscopy, culture and sensitivity.
Results: Equal percentage in cases which delivered in the same day and not responding to the drugs only 2 cases in each group present 8.0%. In the next day 3 cases delivered in group 1 present 12.0% and 1 case in group 2 present 4.0%. The delivery in the first 48 hours present failure rate of the drug, in our study the failure rate was 20% in group 1 and 12% in group 2. Labour by 7 day occur in 2 cases in each group presenting 8.0% in each group. Labour by 14 day occurred in 2 cases in group 1 and 1 case in group 2 presenting 8% and 4% respectively. Labour at 32 week occurred in 3 cases in group 1 and 2 cases in group 2 presenting 12% and 8% respectively. Labour at 34 week occurred in 4 cases in each group presenting 16% to each group. Labour at 37 week occurred in 6 cases in group 1 and 8 cases in group 2 presenting 24% and 32% respectively. Labour by 32 week occurred in 6 cases in group 1 and 2 cases in group 2 presenting 24 and 8 respectively. Labour by 34 week occurred in 2 cases in group 1 and 3 cases in group 2 presenting 8% and 12% respectively. Labour by 37 week occurred in 4 cases in group 1 and 6 cases in group 2 presenting 16% and 24%.
Conclusion: Both glyceryltrinitrate and ritodrine were comparable in prolongation of gestation in patients in preterm labour, both in duration and in terms of success. The advantages of glyceryltrinitrate patch over ritodrine are lesser side effects and simplicity of administration and it also allows the patient to remain ambulatory.