Nusinersen

eMC §4.2 (Spinraza 12 mg solution for injection). Treatment should only be initiated by a physician experienced in the management of spinal muscular atrophy (SMA); the decision to treat should be based on an individualised expert evaluation of expected benefit against risk. Patients with profound hypotonia and respiratory failure at birth, where the product has not been studied, may not experience a clinically meaningful benefit. ADMINISTRATION: it is recommended that a volume of cerebrospinal fluid equivalent to the volume to be injected is removed prior to administration; sedation may be required as indicated by the clinical condition; ultrasound or other imaging may be considered to guide intrathecal administration, particularly in younger patients and in patients with scoliosis; the injection must not be given into areas of skin showing signs of infection or inflammation. DURATION: information on long-term efficacy is not available - the need to continue therapy should be reviewed regularly and considered on an individual basis. MISSED OR DELAYED DOSES (eMC §4.2 Table 1) - loading dose: give the delayed or missed loading dose as soon as possible with at least 14 days between doses, then continue subsequent doses at the prescribed intervals from the last dose. Maintenance dose: if more than 4 to less than 8 months from the last dose, give the delayed dose as soon as possible then the next dose on the original scheduled date provided the two doses are at least 14 days apart; if 8 to less than 16 months, give the missed dose as soon as possible then the next dose 14 days later; if 16 to less than 40 months, give the missed dose as soon as possible then two further doses 14 days apart; if 40 months or more, give the entire loading regimen again on the prescribed intervals (Days 0, 14, 28 and 63). In each case a maintenance dose is then given 4 months after the last dose and repeated every 4 months. HEPATIC IMPAIRMENT: not studied; nusinersen is not metabolised via the hepatic cytochrome P450 system so dose adjustment is unlikely to be required. PAEDIATRIC: the eMC posology gives a single fixed 12 mg dose with no weight-based or age-based adjustment; the US label states safety and effectiveness have been established in paediatric patients from newborn to 17 years. There is no per-kg dose in the source, so no structured paediatric dose is given here - verify any under-18 use against a children's formulary. US LABELLING DIFFERENCE (openFDA, Spinraza, Biogen, label date 2026-03-31): the US prescribing information offers two regimens - a Low Dose Regimen (one 12 mg loading dose every 14 days for three doses, then a fourth 12 mg loading dose 30 days after the third, then 12 mg once every 4 months) and a High Dose Regimen (one 50 mg loading dose followed by a second 50 mg loading dose 14 days later, then 28 mg once every 4 months). The high-dose regimen and the 28 mg and 50 mg strengths are NOT in the UK SPC text fetched here - clinician to confirm which regimen and strengths are licensed locally. The US label also requires a platelet count, coagulation testing (prothrombin time; activated partial thromboplastin time) and quantitative spot urine protein testing at baseline and before each dose.