Romiplostim

eMC (Nplate 125 micrograms powder for solution for injection vial). UNITS ARE MICROGRAMS PER KG, NOT MILLIGRAMS. Treatment should remain under the supervision of a physician experienced in haematological diseases. DOSE CALCULATION: individual patient dose (micrograms) = weight (kg) x dose in micrograms/kg; actual body weight at initiation of treatment should always be used when calculating the initial dose. In adults, future dose adjustments are based on changes in platelet count only. MONITORING: assess platelet counts weekly until a stable count (>= 50 x 10^9/L for at least 4 weeks without dose adjustment) is achieved, then monthly. DOSE ADJUSTMENT TABLE: platelet count < 50 x 10^9/L — increase the once-weekly dose by 1 microgram/kg; > 150 x 10^9/L for two consecutive weeks — decrease the once-weekly dose by 1 microgram/kg; > 250 x 10^9/L — do not administer, continue weekly platelet assessment and, once the count has fallen below 150 x 10^9/L, resume with the once-weekly dose reduced by 1 microgram/kg. Because of interindividual variability, platelet counts may fall abruptly below 50 x 10^9/L after dose reduction or discontinuation; higher cut-offs for dose reduction (200 x 10^9/L) and treatment interruption (400 x 10^9/L) may be considered according to medical judgement. DISCONTINUATION: stop treatment if the platelet count does not increase to a level sufficient to avoid clinically important bleeding after four weeks of therapy at the highest weekly dose of 10 micrograms/kg. Thrombocytopenia is likely to recur on discontinuation. PREPARATION: if the individual patient dose is >= 23 micrograms, reconstitute (resulting concentration 500 micrograms/mL) and volume (mL) = dose (micrograms) / 500; if the dose is < 23 micrograms, reconstitution AND dilution are required (resulting concentration 125 micrograms/mL) and volume (mL) = dose (micrograms) / 125 — round volume to the nearest hundredth mL and use a syringe with 0.01 mL graduations. HEPATIC IMPAIRMENT: should not be used in moderate to severe hepatic impairment (Child-Pugh score >= 7) unless the expected benefit outweighs the identified risk of portal venous thrombosis; if used, monitor platelet count closely. ELDERLY (>= 65 years): no adjustment of the dosing regimen is required, but care is advised given the small numbers studied.

UNIT IS MICROGRAMS PER KG, NOT MILLIGRAMS. The SPC gives a single posology: 'The initial dose of romiplostim is 1 mcg/kg based on actual body weight', and works a paediatric example ('10 kg patient is initiated at 1 mcg/kg' = 10 micrograms, which is < 23 micrograms and therefore requires dilution to 125 micrograms/mL). In paediatric patients, future dose adjustments are based on changes in platelet counts AND changes in body weight — reassessment of body weight is recommended every 12 weeks (in adults, platelet count only). Safety and efficacy in children under the age of one year have not been established. Self-administration of romiplostim is not allowed for paediatric patients. Clinician to verify against a children's formulary before use.