Multiplying a daily dose by seven is arithmetic, not a dosing decision. When a weekly total is useful and when it means nothing.
Key points
- 01Multiplying by seven is arithmetic, not a schedule. A weekly total is easy to compute and tells you how much drug a week consumes. It does not tell you that the same amount can be given in one injection, and treating the two as interchangeable is the single most dangerous move in this topic.
- 02Half-life is what makes a weekly schedule possible. Medicines dosed once weekly are engineered to persist between injections, which is a property of the molecule and formulation. A medicine designed for daily administration does not acquire that property by being multiplied by seven.
- 03Where the weekly total is genuinely useful: planning a vial. If you know the weekly consumption in milligrams, you know how long a vial lasts and whether it will be used up inside its in-use window. That is a supply question, and it is the main honest use of the calculation.
- 04Comparing two schedules needs the same window. To compare a daily regimen with a weekly one on paper, express both over the same period. That comparison is a way of understanding what you are reading in a label or a study, not a way of designing a substitute regimen.
- 05Missed days do not roll forward. A weekly total is a sum, not a budget you are entitled to catch up on. Skipping days and then giving a larger dose to make up the difference is not how the arithmetic translates back to a body, and our missed-dose guidance covers the correct catch-up rules.
- 06Any change of schedule belongs with your prescriber. Whether a medicine can move between daily and weekly administration, at what dose, and with what titration is a prescribing decision informed by the approved labelling. This page explains the arithmetic and stops there.
Frequently asked questions
Can I take my daily dose once a week instead?+
Not as a self-made change. Whether a medicine can be given weekly depends on its half-life and formulation, and it is decided by the approved labelling and your prescriber. Multiplying by seven answers an arithmetic question only. Not medical advice.
How do I calculate a weekly total from a daily dose?+
Multiply the daily dose by the number of doses in the week, which is seven for a once-daily regimen. The result is useful for working out how long a vial will last and for comparing regimens on paper.
Why is the weekly total still worth knowing?+
Because supply planning runs on it. Weekly consumption tells you how many vials a month needs and whether an opened vial will be finished inside its in-use period, which is a logistics question rather than a dosing one.
I missed several days. Do I add them to the next dose?+
No. A weekly figure is a description of a schedule, not an allowance to catch up. Follow the catch-up guidance for your specific medicine and speak to your prescriber if several doses were missed.