Neonatal abstinence and withdrawal syndromes — formative SAQs

SAQ 1 — The methadone-exposed infant at 48 hours (10 marks)

A 36-week infant whose mother is on a supervised methadone maintenance programme (90 mg/day, stable, HIV-negative, non-smoker) has been rooming-in and breastfeeding since birth. At 48 hours of life the infant has a high-pitched cry, a fine tremor when handled, sweating, a stuffy nose and poor feeding; the bedside glucose is 2.2 mmol/L. ^[3]

a) Explain the neuroadaptive mechanism by which methadone produces neonatal withdrawal, and state why it peaks at 48–72 hours. (3 marks) ^[3]

Chronic in-utero opioid exposure suppresses the locus coeruleus and dampens neuronal firing at the μ-opioid receptor; the fetal brain compensates by up-regulating μ-receptor density and raising the tonic activity of noradrenergic and dopaminergic pathways so that it can keep firing in the presence of the drug. When the cord is clamped the methadone supply ceases abruptly, but the compensatory up-regulation persists, and the unopposed surge of CNS and autonomic activity produces the triad of CNS hyperexcitability, autonomic overdrive and gastrointestinal dysregulation. Methadone has a long half-life, so the withdrawal characteristically peaks at 48–72 hours — later than short-acting opioids — which is why methadone-exposed infants are observed in hospital for at least 5–7 days. ^[3]

b) Apply the Eat, Sleep, Console functional assessment to this infant, and state the treatment decision it drives. (2 marks) ^[7]

The three functional questions are whether the infant can eat at least one ounce per feed, sleep at least one hour, and be consoled within ten minutes. This infant is taking only a fraction of the expected volume (eat goal failing) and has fractured sleep (sleep goal failing), so the functional assessment indicates that the infant is not meeting the goals. The decision flow is to intensify non-pharmacologic care first — low stimulation, swaddling, skin-to-skin, lactation support — and to reach for morphine or buprenorphine only if the infant still cannot eat, sleep or be consoled despite that. ^[7]

c) Give your immediate management, including the metabolic priority. (3 marks) ^[3]

The metabolic priority is to correct the hypoglycaemia: give a dextrose bolus (typically 2 mL/kg of 10% dextrose) followed by a continuous infusion, and recheck the glucose. Exclude the mimics by checking electrolytes (calcium, magnesium) and performing a septic screen if the infant is unwell. Intensify the non-pharmacologic bundle — continue rooming-in and demand breastfeeding (the mother is stable, HIV-negative and on supervised methadone, so breastfeeding is endorsed and protective), maintain a low-stimulation environment, swaddle and offer skin-to-skin contact. Escalate to first-line pharmacotherapy (oral morphine or sublingual buprenorphine) only if the infant fails to meet the functional goals despite maximal conservative care. ^{[3] [9]}

d) Compare oral morphine with sublingual buprenorphine as first-line pharmacotherapy, citing the evidence. (2 marks) ^[6]

Oral morphine is the long-standing first line: it is started at a defined initial dose (typically 0.05 mg/kg/dose every 3–4 hours) and titrated upward in set increments until the infant is settled and feeding. Sublingual buprenorphine is the evidence-based alternative; the Kraft NEJM 2017 randomised trial showed that buprenorphine shortened the duration of treatment and length of stay relative to morphine. Buprenorphine requires an extemporaneous preparation and attention to its complex pharmacology, but it offers a faster wean. Once stable for 24–48 hours, the opioid is weaned by 10–20 percent daily. Phenobarbital should not be used as a sole agent for pure opioid withdrawal. ^{[6] [3]}