United States
Hong KongBiennial inventory
A biennial inventory of controlled substances may be taken on any date within two years of the previous biennial inventory date, under 21 CFR 1304.11.
A short topic built on one word that people get wrong.
The rule
A biennial inventory may be taken on any date which is within two years of the previous biennial inventory date. That is 21 CFR 1304.11.
Biannual means twice a year and biennial means every two years, and they are one letter apart. The regulation is unambiguous about the interval, and a question offering both readings as options is testing exactly this.
The flexibility in the date
It does not have to be an anniversary. Any date within two years of the previous one satisfies the requirement, which lets a pharmacy schedule it conveniently.
What it cannot do is drift beyond two years.
The initial inventory
A registrant takes an inventory when they first engage in controlled substance activity. The biennial cycle runs from there.
What is counted
Schedule II substances are counted exactly. For Schedules III to V an estimated count is permitted in defined circumstances, with an exact count required for larger container sizes.
The distinction reflects the same logic as everywhere else in this part: the tighter the schedule, the tighter the control.
Why it matters
Inventory is one of the three legs of reconstruction - what came in, what went out, what is held. Without it the other two cannot be reconciled.
And the records
Inventory records are kept for at least two years like other controlled substance records, under 21 CFR 1304.04.
Common questions
How often is a biennial inventory required?
Every two years. Any date within two years of the previous one.
Does biennial mean twice a year?
No, that is biannual. Biennial is every two years.
Does it have to be on an anniversary?
No. Any date within the two years satisfies it.
How are Schedule II items counted?
Exactly. Schedules III to V permit an estimated count in defined circumstances.
How long are inventory records kept?
At least two years, under 21 CFR 1304.04.