Agranulocytosis associated with intravenous ritodrine hydrochloride therapy: Two case reports by different mechanisms

Ritodrine-Induced Agranulocytosis: A Case Report and Literature Review

Ritodrine hydrochloride is used for preterm labor, although serious side effects, including agranulocytosis, are reported. We report a case of ritodrine hydrochloride-induced agranulocytosis accompanied by bacteremia due to catheter infection. At 24 weeks of gestation, a female patient presented due to threatened premature labor and was administered continuous intravenous infusion of ritodrine hydrochloride. On day 36 after starting intravenous ritodrine hydrochloride, she was diagnosed with agranulocytosis. The white blood cell and granulocyte count nadirs were 1,660/μl and 438/μl. The cumulative dose of ritodrine hydrochloride was 2,610 mg. Ritodrine therapy was immediately stopped, and she was given an intravenous injection of antibiotics and granulocyte colony-stimulating factor. From her blood culture, methicillin-sensitive Staphylococcus aureus was detected. However, she started vaginal delivery two days after we stopped the ritodrine infusion. When using ritodrine hydrochloride, it is necessary to frequently check the white blood cell count, regardless of the total dose and treatment period.

Incidence and risk factors of neonatal hypoglycemia after ritodrine therapy in premature labor: a retrospective cohort study

Background

Ritodrine hydrochloride (RD), a β2-adrenergic agonist, is widely used as a tocolytic medication to suppress premature labor, but can cause neonatal hypoglycemia, a potentially severe side effect. We examined the incidence and risk factors of neonatal hypoglycemia following maternal intravenous administration of RD.

Methods

This was a retrospective study of neonates, who had birth weight of ≥2000 g and were delivered at 36 weeks gestation or later in Kanazawa University Hospital from August 2013 to July 2016. We defined neonatal hypoglycemia as blood glucose level < 50 mg/dL. Neonates who were delivered without maternal intravenous RD or who were delivered 8 days or more after stopping maternal RD or who received oral RD were defined as the RD non-administration group, while those delivered within 7 days after stopping maternal RD were defined as the RD intravenous administration group. We examined the incidence and risk factors of RD-induced neonatal hypoglycemia by comparing these two groups.

Results

We enrolled 603 neonates in this study; 504 (83.6%) showed no neonatal hypoglycemia, while 99 (16.4%) exhibited neonatal hypoglycemia. The incidence of neonatal hypoglycemia was significantly higher (61.7%; 58/94) in the RD intravenous administration group than in the RD non-administration group (8.1%; 41/509) (p < 0.001). Binomial logistic regression analysis in the RD intravenous administration group showed that maternal age over 35 years (AOR: 3.385; 95% CI, 1.082–10.588, p = 0.036) and the interval to delivery from stopping intravenous administration of RD (AOR: 0.974; 95% CI, 0.953–0.996, p = 0.020) were independent factors associated with neonatal hypoglycemia. The cut-off value of the interval to predict the incidence of neonatal hypoglycemia was about 6 h (sensitivity 82.8%, specificity 63.9%).

Conclusions

The incidence of neonatal hypoglycemia was significantly increased by maternal intravenous administration of RD. We newly identified maternal age (over 35 years) and the interval to delivery from stopping intravenous administration of RD (within 6 h) as independent risk factors for neonatal hypoglycemia following maternal intravenous administration of RD. In cases with these risk factors, careful blood glucose monitoring is recommended for early detection and treatment of neonatal hypoglycemia.

Successful treatment with granulocyte-colony stimulating factor for ritodrine-induced neutropenia in a twin pregnancy

OBJECTIVE

Neutropenia developed after continuous intravenous infusion of ritodrine hydrochloride (Yutopar) for preterm uterine contractions in a twin pregnancy. We successfully returned the low neutrophil count to the normal range after discontinuation of infusion of ritodrine and treatment with granulocyte colony stimulating factor (G-CSF).

CASE REPORT

A 34-year-old woman with twin pregnancy was treated with ritodrine for preterm uterine contractions at 27 weeks and 6 days gestation. Neutropenia developed after continuous intravenous infusion of ritodrine for about 4 weeks. We ceased the ritodrine infusion immediately and treated the neutropenia with G-CSF. A cesarean delivery was performed the day after cessation of the ritodrine infusion because of uncontrolled preterm labor. There were no adverse side effects or infectious complications in the mother or the newborns. The maternal neutrophil count recovered to the normal range 4 days after administration of G-CSF.

CONCLUSION

Based on prior case reports and the clinical presentation of our case, G-CSF may be a useful treatment for pregnant women with ritodrine-induced neutropenia. However, more clinical studies are required to confirm the safety and efficacy of this treatment.

The Association between Prenatal Yoga and the Administration of Ritodrine Hydrochloride during Pregnancy: An Adjunct Study of the Japan Environment and Children's Study

Introduction

While the beneficial effects of prenatal yoga have been reported in recent years, little is known about its effectiveness in pregnant Japanese women. Despite several adverse effects, ritodrine hydrochloride is frequently prescribed to suppress preterm labor in Japan, and its usage may therefore indicate cases of preterm labor. This study aimed to clarify the association between prenatal yoga and ritodrine hydrochloride use during pregnancy.

Methods

An observational study was conducted as an adjunct study by the Hokkaido unit of the Japan Environment and Children’s Study. Information on prenatal yoga practice was collected using a self-questionnaire between March 21, 2012, and July 7, 2015, targeting women who had recently delivered. Ritodrine hydrochloride use was identified from medical records. A total of 2,692 women were analyzed using logistic regression models that adjusted for possible confounders.

Results

There were 567 (21.1%) women who practiced prenatal yoga, which was associated with a lower risk of ritodrine hydrochloride use (adjusted odds ratio [OR] 0.77; 95% CI 0.61–0.98). This was especially evident in women with a total practice duration that exceeded 900 minutes throughout their pregnancy (adjusted OR 0.54; 95% CI 0.38–0.76). A sensitivity analysis that excluded patients with threatened abortion during the study period produced similar results.

Conclusions

Prenatal yoga was associated with a lower risk of ritodrine hydrochloride use, particularly in women with more than 900 minutes of practice time over the course of their pregnancy. Prenatal yoga may be a beneficial option for pregnant women in the selection of alternative therapies.

Drug-induced lymphocyte stimulation test in the prediction of drug-induced hypersensitivity to antituberculosis drugs

Antituberculosis (TB) chemotherapeutic drugs may cause a variety of adverse drug reactions (ADRs). To assess the potential of drug-induced lymphocyte stimulation test (DLST) in screening ADRs in patients treated with anti-TB drugs, we performed DLST in 272 TB patients (176 cases with ADRs and 96 controls without ADRs) treated with anti-TB drugs isoniazid (INH), rifampicin (RFP), ethambutol (EMB), and pyrazinamide (PZA). The ADRs were diagnosed by drug provocation test based on clinical and laboratory examinations. The sensitivities of DLST in the diagnosis of INH-, RFP-, EMB-, or PZA-induced ADRs were 57.8%, 37.1%, 42.4%, and 23.1%, respectively, with the corresponding specificities being 93.4%, 94.0%, 97.5%, and 98.8%. DLST has high specificity and limited sensitivity in the diagnosis of anti-TB drug-induced ADRs. In combination with clinical observation and drug use history, DLST could have a predictive validity of ADRs, especially when a positive result is obtained.