Phenobarbital

What is phenobarbital?

Phenobarbital is a medication used to control or prevent certain types of seizures.

You may hear phenobarbital called by its brand name, PMS-phenobarbital. Phenobarbital comes in liquid, tablet, or injection forms.

Before giving phenobarbital to your child?

Tell your child's doctor if your child has:

• allergies to phenobarbital
• porphyria (a problem with enzymes that make red blood cells)
• difficulty breathing

Talk with your child's doctor or pharmacist if your child has any of the following conditions. Precautions may need to be taken with this medicine if your child has:

• kidney disease
• liver disease

How should you give your child phenobarbital?

• Give phenobarbital exactly as your child's doctor or pharmacist tells you, even if your child seems well. Talk to your child's doctor before you stop giving this medication for any reason.
• Give phenobarbital at the same time every day. Pick a time that is easy for you so that you do not miss doses.
• Give phenobarbital with food or milk if possible to prevent stomach upset.
• If your child is taking liquid phenobarbital, measure out each dose with the special spoon, dropper or syringe that the pharmacist gave you.
• Mix the liquid phenobarbital with a small amount of water, milk or juice just before giving it to your child.
• If your child has a feeding tube, consider diluting the liquid phenobarbital with water before giving it through the tube. If possible, give extra flushes of water (10 to 20 ml) before and after giving the phenobarbital to prevent clogging.

What should you do if your child misses a dose of phenobarbital?

• Give the missed dose as soon as you remember.
• If it is almost time for the next dose, skip the missed dose. Give the next dose at the regular time.
• Do not give your child 2 doses to make up for 1 missed dose.

How long does phenobarbital take to work?

Phenobarbital make take up to several weeks to reach its full effect.

What are the possible side effects of phenobarbital?

Your child may have some of these side effects while they take phenobarbital. Check with your child's doctor if your child continues to have any of these side effects, if they do not go away, or if they bother your child:

• dizziness, drowsiness, headache, or lightheadedness
• nausea, vomiting, constipation, or diarrhea
• feeling nervous or irritable
• trouble sleeping

Most of the following side effects are not common, but they may be a sign of a serious problem. Call your child's doctor right away or take your child to Emergency if your child has any of these side effects:

• skin rash, itching
• sore throat
• fever, chills
• unusual bruising or bleeding
• tingling in hands and feet
• yellow skin or eyes
• dark urine
• chest, joint or muscle pain
• a change in your child's seizure pattern

What safety measures should you take when your child is using phenobarbital?

There are some medicines that should not be taken together with phenobarbital or in some cases the dose of phenobarbital or the other medicine may need to be adjusted if they are taken together. It is important that you tell your doctor and pharmacist if your child takes any other medications (prescription, over the counter, or herbal) including:

• benzodiazepines such as lorazepam (Ativan) and diazepam (Valium)
• ethosuximide (Zarontin)
• lamotrigine (Lamictal)
• valproic acid (Depakene, Epival)
• voriconazole (Vfend)
• warfarin (Coumadin)

Blood levels of phenobarbital may be checked routinely. On the day that your child is having a level checked, do not give the next dose until the blood has been drawn.

Before your child has any medical tests or procedures, tell the doctor in charge that your child is taking phenobarbital.

Phenobarbital may make your child dizzy, drowsy, or less alert than normal, especially when your child first starts taking it. Tell your child's teacher that they are taking this medication.

Keeping a record of your child's seizures, behaviour and school performance can help to identify the best dose of this medication for your child.

What other important information should you know about phenobarbital?

• Do not share your child's medicine with others. Do not give anyone else's medicine to your child.
• Make sure you always have enough phenobarbital to last through weekends, holidays, and vacations. Call your pharmacy at least 2 days before your child runs out of medicine to order refills.
• Keep phenobarbital in its original bottle at room temperature in a cool, dry place away from sunlight. Do NOT store it in the bathroom or kitchen.
• Do not keep any medicines that are out of date. Check with your pharmacist about the best way to throw away outdated or leftover medicines.
  

Keep phenobarbital out of your child’s sight and reach and locked up in a safe place. If your child takes too much phenobarbital, call your local Poison Information Centre at one of these numbers. These calls are free. 

• Call 1-844 POISON-X, or 1-844-764-7669, from anywhere in Canada except Quebec.
• Call 1-800-463-5060 if you live in Quebec.