Introduction
Anaphylaxis is a rapid onset, systemic allergic reaction involving activation of mast cells and/or basophils which is potentially life threatening (1). It is typically triggered by insects bite, rubber latex, foods and drugs through IgE activation (1). The estimated life time prevalence of anaphylaxis is between 0.05% and 2.0% (2). The prevalence of maternal anaphylaxis was 2.7 cases per 1,00,000 deliveries (3). However, there is no literature on tramadol causing anaphylaxis in pregnancy.
Tramadol is a centrally acting opioid analgesics that is commonly used for mild to moderate pain relief. Tramadol is in step 2 WHO step ladder of analgesic used for mild to moderate pain (4).
Tramadol has modest µ opioid receptors affinity and no affinity for δ or κ opioid receptors. The affinity of tramadol for µ receptors is 6000-fold less than that of morphine. The metabolite M1 has 300-fold higher affinity than tramadol but it is still much lower than that of morphine. Tramadol also inhibits neuronal reuptake of norephinephrine and serotonin (5). It is commonly used as labour analgesics in Bhutan.
Allergic reactions to tramadol whether anaphylaxis or IgE mediated is rare, and considered safe for use (5). There are few case reports of tramadol induced anaphylaxis in non-pregnant patients (6,7).Therefore, this is a first report on tramadol induced intrapartum maternal respiratory arrest while the nation was in lockdown due to community transmission of SARS-CoV-19 from Bhutan. In this case, diagnosis of maternal collapse due to IV tramadol use is made on the basis of time between the drug administration and the patient’s reaction.