Which dosing interval is indicated by q 12 h?

Which dosing interval is indicated by q 12 h?

• A. Every 6 hours
• B. Twice daily
• C. Every 12 hours
• D. Every 24 hours

Answer: (C)

q12h means the drug is given every 12 hours. The q stands for quaque, meaning “every,” and 12 h specifies the interval. This corresponds to a twice-daily schedule, designed to keep drug levels more stable than once daily without increasing dosing frequency. Dosing every 6 hours would be q6h, and every 24 hours would be q24h, which are different intervals. While “twice daily” conveys the same practical frequency, the explicit interval indicated by the abbreviation q12h is every 12 hours.

q12h means the drug is given every 12 hours. The q stands for quaque, meaning “every,” and 12 h specifies the interval. This corresponds to a twice-daily schedule, designed to keep drug levels more stable than once daily without increasing dosing frequency.

Dosing every 6 hours would be q6h, and every 24 hours would be q24h, which are different intervals. While “twice daily” conveys the same practical frequency, the explicit interval indicated by the abbreviation q12h is every 12 hours.