Active Ingredient: Romiplostim
Romiplostim is indicated for chronic immune (idiopathic) thrombocytopenic purpura (ITP) patients one year of age and older who are refractory to other treatments (e.g. corticosteroids, immunoglobulins).
For this indication, competent medicine agencies globally authorize below treatments:
1 - 1 ug per kg of body weight
From 1 To 1 ug per kg of body weight once every 7 day(s)
Romiplostim should be administered once weekly as a subcutaneous injection.
The initial dose of romiplostim is 1 mcg/kg based on actual body weight.
The volume of romiplostim to administer is calculated based on body weight, dose required, and concentration of product.
Table 1. Guidelines for calculating individual patient dose and volume of romiplostim to administer:
|Individual patient dose (mcg)
|Individual patient dose (mcg) = weight (kg) x dose in mcg/kg
|Actual body weight at initiation of treatment should always be used when calculating initial dose.
|In adults, future dose adjustments are based on changes in platelet counts only.
|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.
|If individual patient dose is ≥23 mcg
|Reconstitute lyophilised product as described in section 6.6. The resulting concentration is 500 mcg/mL.
|Volume to administer (mL) = Individual patient dose (mcg) / 500 mcg/mL (Round volume to the nearest hundredth mL)
|If individual patient dose is <23 mcg
|Dilution is required to ensure accurate dosing. Reconstitute lyophilised product and then dilute the product. The resulting concentration is 125 mcg/mL.
|Volume to administer (mL) = Individual patient dose (mcg) / 125 mcg/mL (Round volume to the nearest hundredth mL)
|10 kg patient is initiated at 1 mcg/kg of romiplostim.
|Individual patient dose (mcg) = 10 kg x 1 mcg/kg = 10 mcg
|Because the dose is <23 mcg, dilution is required to ensure accurate dosing. Reconstitute lyophilised product and then dilute the product. The resulting concentration is 125 mcg/mL.
|Volume to administer (mL) = 10 mcg / 125 mcg/mL = 0.08 mL
A subject’s actual body weight at initiation of therapy should be used to calculate dose. The once weekly dose of romiplostim should be increased by increments of 1 mcg/kg until the patient achieves a platelet count ≥50 × 109/L. Platelet counts should be assessed weekly until a stable platelet count (≥50 × 109/L for at least 4 weeks without dose adjustment) has been achieved. Platelet counts should be assessed monthly thereafter and appropriate dose adjustments made as per the dose adjustment table (table 2) in order to maintain platelet counts within the recommended range. See table 2 below for dose adjustment and monitoring. A maximum once weekly dose of 10 mcg/kg should not be exceeded.
Table 2. Dose adjustment guidance based on platelet count:
|Platelet count (x 109/l)
|Increase once weekly dose by 1 mcg/kg
|>150 for two consecutive weeks
|Decrease once weekly dose by 1 mcg/kg
|Do not administer, continue to assess the platelet count weekly.
|After the platelet count has fallen to <150 × 109/1, resume dosing with once weekly dose reduced by 1 mcg/kg
Due to the interindividual variable platelet response, in some patients platelet count may abruptly fall below 50 × 109/L after dose reduction or treatment discontinuation. In these cases, if clinically appropriate, higher cut-off levels of platelet count for dose reduction (200 × 109/L) and treatment interruption (400 × 109/L) may be considered according to medical judgement.
A loss of response or failure to maintain a platelet response with romiplostim within the recommended dosing range should prompt a search for causative factors.
Treatment with romiplostim should be discontinued if the platelet count does not increase to a level sufficient to avoid clinically important bleeding after four weeks of romiplostim therapy at the highest weekly dose of 10 mcg/kg.
Patients should be clinically evaluated periodically and continuation of treatment should be decided on an individual basis by the treating physician, and in non-splenectomised patients this should include evaluation relative to splenectomy. The reoccurrence of thrombocytopenia is likely upon discontinuation of treatment.
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