Short answer: Romosozumab has a half-life of about 12.8 days (effective). Levels peak median 5 days (2 to 7 days) after a dose. People vary, so treat these as estimates.
Romosozumab is an antibody that blocks sclerostin, a protein that holds back bone building. Blocking it raises bone formation and also slows bone breakdown. It is sold as Evenity (Amgen), given as two shots under the skin once a month for 12 months, for osteoporosis in women after menopause at high risk of fracture.
Also known as: Evenity, romosozumab-aqqg.
Evenity comes as 105 mg/1.17 mL single-dose prefilled syringes. Each monthly 210 mg dose is two syringes, injected one after the other at separate sites by a healthcare provider.
The Evenity label approves romosozumab for osteoporosis in women after menopause at high risk of fracture: a past osteoporotic fracture, several risk factors, or other treatments that failed or were not tolerated. Label dosing is 210 mg under the skin once a month for 12 doses, with calcium and vitamin D. Use stops at 12 doses because its bone-building effect wanes; an anti-resorptive drug may then be considered. A missed dose is given as soon as it can be rescheduled, then monthly from that date.
Evenity has a boxed warning titled "Potential risk of myocardial infarction, stroke and cardiovascular death": in a trial against alendronate, major heart events were more common on Evenity. It is not started within a year of a heart attack or stroke and is stopped if one happens. Other warnings cover allergic reactions, low calcium, jaw bone death and unusual thigh fractures. In the 7,180-woman placebo trial, joint pain was 13.1% vs 12.1% and headache 6.6% vs 5.8%. Full numbers are on the Evenity side effects, Evenity dosing schedule, missed Evenity dose and Evenity storage pages. Comparisons: Evenity vs Forteo and Prolia vs Evenity.
The Evenity label gives a median time to peak of 5 days (range 2 to 7) after an injection, and a mean effective half-life of 12.8 days after three monthly doses at the approved level. Steady levels were reached by month 3. Its handling is nonlinear: clearance falls as the dose rises.
Numbers shown are taken from the source above. Half-life varies from person to person.
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