Phenobarbital (CAS 50-06-6): storage and disposal
Phenobarbital is a long established barbiturate held by pharmacies and clinics for seizure treatment, and by veterinary practices, where it is a common epilepsy tablet for dogs. It is a Schedule 3, Class B controlled drug. The substance is toxic if swallowed, may cause an allergic skin reaction, is suspected of causing cancer and may damage fertility or the unborn child. Those hazards matter for damaged stock, but legal control decides the route, which begins with a manual enquiry.
- CAS number
- 50-06-6
- Form
- Solid
- Storage class
- Toxic
- Signal word
- Danger
- Usual EWC code, laboratory stock
- 16 05 06*
Acute toxicity
Serious health hazard
This chemical is a manual enquiry
This is a controlled drug. Controlled drugs have their own legal requirements, which depend on the schedule and can cover storage, witnessing and destruction, so they cannot be priced through a standard form.
UK Misuse of Drugs Regulations 2001: Schedule 3, Class B.
It cannot be priced through a form. Please do not open or move it. Call us or send an enquiry and we will talk through the next step, which depends on what it is. Keep following your own procedures for controlled drugs, radioactive materials, gases and asbestos.
What to do this week
- Leave it where it is. If it looks old, crystalline or damaged, do not open or move it and keep people away from the shelf. If there is immediate danger, such as a leak, fumes or a fire, leave the area and call 999.
- Write down the label wording, the rough age and where it is stored, from a safe distance.
- Send us those details, and a photo if you can take one without touching it.
Safe storage in a school or lab
Keep phenobarbital separate from incompatible chemicals, particularly oxidisers, and retain it in suitable labelled storage. In a real cupboard the larger concern is who can reach it. Veterinary practices often repeat-dispense it for long courses, so opened tubs and owner returns need secure storage under the practice's medicines procedures, separate from stock for dispensing, with accurate records maintained. Keep tablets in the labelled pack. Tablets decanted for counting leave dust on trays, and repeated skin contact with that dust matters for a skin sensitiser with fertility and cancer classifications. Injection vials or ampoules should remain in their carton, out of direct light and clearly separate from tablet stock.
How to tell it has deteriorated
Plain white tablets and a clear, colourless injection are what you would expect, although some makers tint their tablets, so check against the pack description. Tablets that have crumbled, gone soft or left powder in the tub suggest damp and rough handling. Dark spotting is not normal either. In the injection, haze, particles or crystals show the contents are no longer as supplied, and the ampoule should not be opened for a closer look. Otherwise phenobarbital gives few visible signs, because a tablet long past its date can look unchanged. A sticky ring on a tub lid, a label faded by the window or an owner's return with a smudged dose label deserves recording too.
How it is disposed of
This does not go through our standard collection route. It is arranged by manual enquiry, and never goes down the drain or into general waste.
Tipping old tablets into a bin or flushing injection down a sink is never acceptable. Nor should anyone crush or mix stock to disguise it. Disposal is a manual enquiry, because this site does not quote it online and a chemical collection does not cover it. The Misuse of Drugs Regulations 2001 govern destruction, and in healthcare the accountable officer or responsible pharmacist decides. Routine Schedule 3 stock destruction does not normally need an authorised witness, although local procedures may ask for one. Veterinary surgeries should say so, since 18 02 08 normally applies to them and 18 01 09 to human healthcare. Part-used tubs and owner returns should be listed separately from sealed packs. Where several consulting rooms hold stock, ask for a store assessment and leave each item secured in place until then.
| Usual EWC code, laboratory stock | 16 05 06* |
|---|---|
| Discarded organic chemical, not a laboratory pack | 16 05 08* |
| Human healthcare setting | 18 01 09 |
| Veterinary setting | 18 02 08 |
| Usually classed as hazardous waste | Yes |
The code depends on where the waste came from and what it contains, and classifying it is the producer's duty. Use the waste code finder to see why.
Do not store with
- OxidiserToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
- AcidToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
Named chemicals to keep apart
- Acetic acidToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
- Calcium hypochloriteToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
- Hydrochloric acidToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
- Hydrogen peroxideToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
- Nitric acidToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
- Potassium nitrateToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
- Potassium permanganateToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
- Sulfuric acidToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
Common quantities
Usually held as: tablets, injection.
Tell us the container size and how many you hold. An estimate is enough to start with, and some items cannot be priced until someone has looked at them.
Where it is commonly held
Hazard statements
- H301 Toxic if swallowed.
- H317 May cause an allergic skin reaction.
- H351 Suspected of causing cancer.
- H360 May damage fertility or the unborn child.
Precautionary statements
- P203 Obtain, read and follow all safety instructions before use.
- P261 Avoid breathing dust, fume, gas, mist, vapours or spray.
- P264 Wash hands and exposed skin thoroughly after handling.
- P270 Do not eat, drink or smoke when using this product.
- P272 Contaminated work clothing should not be allowed out of the workplace.
- P280 Wear protective gloves, protective clothing, eye protection and face protection.
- P301+P316 IF SWALLOWED: Get emergency medical help immediately.
- P302+P352 IF ON SKIN: Wash with plenty of water.
- P318 If exposed or concerned, get medical advice.
- P321 Specific treatment (see supplemental first aid instruction on this label).
- P330 Rinse mouth.
- P333+P317 If skin irritation or rash occurs: Get medical help.
- P362+P364 Take off contaminated clothing. And wash it before reuse.
- P405 Store locked up.
- P501 Dispose of contents and container in accordance with local, regional, national and international regulations.
Substance as classified, dilutions may differ.
Questions
A dog owner has returned part-used phenobarbital tablets. Can we reuse them for another patient?
No. Returned medicines have left your control and cannot be reissued. Record the quantity and owner details, secure them in the locked arrangement apart from stock for issue, and include them with your other controlled returns when your practice arranges their destruction through the proper route.
Do staff need extra precautions with broken phenobarbital tablets?
Broken tablets raise more concern than whole ones because the substance is a skin sensitiser and has fertility and cancer classifications, although a tablet contains much less than a bulk powder. Follow your local risk assessment, avoid skin contact and do not sweep up dust dry. Pregnant staff should raise it with their manager.
Is a phenobarbital ampoule with crystals in it still a controlled item?
Yes. A change in appearance does not alter its legal status, and the ampoule stays on your records until its destruction has been arranged and recorded through the proper route. Keep it locked, marked as not for use and unopened, and record the crystals in your enquiry with the batch and expiry date.
What should we say when asking about pure phenobarbital powder?
Tell us it is a pure powder, with the quantity and the container type. It still needs a manual enquiry, because it is a controlled drug.
