Phenobarbital 20mg/5ml Solution

Phenobarbital is a barbiturate that produces nonselective depression of the central nervous system (CNS). It binds to the GABA-A receptor complex, enhancing the inhibitory effects of GABA by increasing the duration of chloride channel opening. This leads to neuronal hyperpolarization and decreased neuronal excitability. It also inhibits excitatory neurotransmitter release and depresses the reticular activating system.

Urgent Side Effects: Seek Medical Help Right Away

Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek immediate medical attention:

Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin (with or without fever)
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Feeling confused
Change in balance
Muscle spasm
Bad dreams
Restlessness
Hallucinations (seeing or hearing things that are not there)
Shortness of breath
Slow heartbeat
Feeling very tired or weak
Severe dizziness or passing out

Severe Skin Reaction: Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis

This rare but serious condition can cause severe health problems and may be life-threatening. Seek medical help immediately if you experience:

Red, swollen, blistered, or peeling skin (with or without fever)
Red or irritated eyes
Sores in your mouth, throat, nose, or eyes

Blood and Liver Disorders

A severe and potentially life-threatening effect has been reported in people taking seizure medications like this one. Contact your doctor right away if you experience:

Swollen glands
Fever
Rash
Painful sores in the mouth or around the eyes
Chest pain
Signs of kidney problems, such as:
+ Unable to pass urine
+ Change in the amount of urine passed
Signs of liver problems, such as:
+ Dark urine
+ Tiredness
+ Decreased appetite
+ Upset stomach or stomach pain
+ Light-colored stools
+ Throwing up
+ Yellow skin or eyes

Other Possible Side Effects

Most people do not experience serious side effects, but some may occur. If you notice any of the following symptoms, contact your doctor or seek medical attention if they bother you or do not go away:

Feeling dizzy or sleepy
Headache
Upset stomach or throwing up
Constipation
Feeling nervous and excitable
* Trouble sleeping

Reporting Side Effects

If you have questions or concerns about side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.

Before Taking This Medication: Important Information to Share with Your Doctor

It is essential to inform your doctor about the following:

Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Describe the allergic reaction you experienced, including the symptoms that occurred.
Certain health conditions, including:
+ Liver disease
+ Breathing problems, such as shortness of breath
+ A history of porphyria
Cardiovascular conditions, including:
+ Heart failure
+ Unstable angina (a type of chest pain)
+ Abnormal heartbeat, such as long QT interval on an electrocardiogram (ECG)
+ Kidney disease
+ Low thyroid function (hypothyroidism)
+ Aortic stenosis (a very narrow heart valve)
If you have recently experienced a heart attack
* If you are taking any medications that can cause abnormal heart rhythms, specifically prolonged QT interval. Many drugs can cause this condition, so consult your doctor or pharmacist if you are unsure.

This list is not exhaustive, and it is crucial to discuss all your medications, including prescription and over-the-counter drugs, natural products, and vitamins, with your doctor and pharmacist. They will help you determine if it is safe to take this medication with your existing health conditions and medications. Never start, stop, or change the dosage of any medication without consulting your doctor.

Important Warnings and Cautions

When taking this medication, it is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, about your treatment.

Risk of Dependence and Withdrawal
The longer you take this medication and the higher the dose, the greater the risk of dependence and withdrawal. Before reducing the dose or stopping the medication, consult your doctor and follow their instructions carefully. Abruptly lowering the dose or stopping the medication can lead to withdrawal, which can be life-threatening. Seek immediate medical attention if you experience any adverse effects.

Tolerance and Dosage
If you have been taking this medication for an extended period or at high doses, it may become less effective, and you may require higher doses to achieve the same effect. This is known as tolerance. If you notice the medication is no longer working as well, contact your doctor. Do not take more than the prescribed dose.

Monitoring and Precautions
If you are taking this medication long-term, your doctor may recommend regular blood tests to monitor your condition. Discuss this with your doctor. Avoid driving and engaging in activities that require alertness until you understand how the medication affects you. Refrain from consuming alcohol while taking this medication. Before using marijuana, cannabis, or prescription or over-the-counter medications that may cause drowsiness, consult your doctor.

Mental Health and Suicidal Thoughts
Like other medications used to treat seizures, this medication may rarely increase the risk of suicidal thoughts or actions, particularly in individuals with a history of suicidal ideation. If you experience new or worsening symptoms such as depression, anxiety, restlessness, irritability, panic attacks, or mood changes, contact your doctor immediately. If you have suicidal thoughts or actions, seek help right away.

Special Considerations
If you are 65 or older, use this medication with caution, as you may be more susceptible to side effects. If the patient is a child, use this medication with caution, as the risk of certain side effects may be higher in children.

Birth Control and Pregnancy
Birth control pills and other hormone-based birth control methods may be less effective while taking this medication. Use two forms of birth control to prevent pregnancy. This medication may harm the unborn baby if taken during pregnancy. If you become pregnant or are planning to become pregnant, contact your doctor immediately. Taking this medication in the third trimester of pregnancy may lead to side effects or withdrawal in the newborn.

Breastfeeding
If you are breastfeeding, consult your doctor to discuss any potential risks to your baby.

Seizure Management
If your seizures change or worsen after starting this medication, consult your doctor to adjust your treatment plan.

• Acute intermittent porphyria
• Severe respiratory depression
• Known hypersensitivity to barbiturates

• Other CNS depressants (alcohol, opioids, benzodiazepines, tricyclic antidepressants): Increased CNS depression, respiratory depression, hypotension.
• Warfarin: Decreased anticoagulant effect due to enzyme induction.
• Oral contraceptives: Decreased efficacy due to enzyme induction.
• Lamotrigine: Decreased lamotrigine levels due to enzyme induction.
• Valproic acid: Increased phenobarbital levels (inhibition of metabolism) and decreased valproic acid levels (enzyme induction).
• Phenytoin: Variable effects; can increase or decrease phenytoin levels, and phenobarbital levels can be affected.
• Carbamazepine: Decreased carbamazepine levels due to enzyme induction.
• Griseofulvin: Decreased griseofulvin levels.
• Doxycycline: Decreased doxycycline levels.
• Corticosteroids: Decreased corticosteroid efficacy.
• Cyclosporine, Tacrolimus: Decreased immunosuppressant levels.

• Antidepressants (SSRIs, MAOIs): Can alter phenobarbital levels or increase CNS depression.
• Antipsychotics: Increased CNS depression.
• Beta-blockers (e.g., propranolol, metoprolol): Decreased beta-blocker levels.
• Calcium channel blockers (e.g., verapamil, nifedipine): Decreased calcium channel blocker levels.
• Digoxin: Decreased digoxin levels.
• Theophylline: Decreased theophylline levels.
• Folic acid: Can decrease phenobarbital levels; phenobarbital can cause folate deficiency.

• Acetaminophen: Increased metabolism of acetaminophen, potentially increasing hepatotoxic metabolite.
• Vitamin D: Can increase vitamin D metabolism, potentially leading to deficiency.

• Excessive sedation
• Drowsiness
• Lethargy
• Ataxia (impaired coordination)
• Nystagmus (involuntary eye movements)
• Slurred speech
• Cognitive impairment
• Behavioral changes (e.g., hyperactivity, irritability, depression, paradoxical excitement in children)
• Skin rash (Stevens-Johnson syndrome, toxic epidermal necrolysis)
• Signs of respiratory depression
• Signs of hepatic dysfunction (jaundice, dark urine, abdominal pain)
• Signs of hematologic abnormalities (unusual bruising, bleeding, fever, sore throat)

Phenobarbital is classified as Pregnancy Category D due to clear evidence of human fetal risk. It is associated with an increased risk of congenital malformations (e.g., cleft lip/palate, cardiac defects, neural tube defects) and a fetal barbiturate syndrome. Neonatal withdrawal symptoms (e.g., irritability, tremors, hypertonia, feeding difficulties) can occur if used during the third trimester. Use only if the potential benefit outweighs the risk, and consider alternative therapies if possible.

Phenobarbital is excreted into breast milk and can cause significant sedation, poor feeding, and weight gain in breastfed infants. The American Academy of Pediatrics considers it a drug for which the effect on the nursing infant is unknown but may be of concern. It is generally not recommended during breastfeeding, or if used, the infant must be closely monitored for adverse effects. Consider alternative agents with lower infant exposure or risk.

Children, especially younger ones, may metabolize phenobarbital faster than adults, requiring higher mg/kg doses. Paradoxical hyperactivity or irritability can occur. Close monitoring of plasma levels and clinical response is essential. Neonates are particularly sensitive to respiratory depression and sedation.

Elderly patients are more sensitive to the CNS depressant effects of phenobarbital (e.g., sedation, confusion, ataxia) and are at increased risk of falls. Lower initial doses and slower titration are recommended. Monitor closely for adverse effects and adjust dose based on clinical response and plasma levels. Renal and hepatic function should be assessed.

• Phenobarbital has a very long half-life, allowing for once-daily dosing in many patients, especially for epilepsy. However, steady-state levels take a long time to achieve (weeks).
• Therapeutic drug monitoring (TDM) is crucial for phenobarbital to ensure efficacy and minimize toxicity, especially given its narrow therapeutic index and significant inter-patient variability.
• Due to its enzyme-inducing properties, phenobarbital can significantly reduce the effectiveness of many other medications, including oral contraceptives, warfarin, and other anticonvulsants. Careful medication reconciliation is essential.
• Withdrawal symptoms can be severe and life-threatening if phenobarbital is discontinued abruptly, especially after prolonged use. Tapering the dose gradually is essential.
• Despite its older age, phenobarbital remains a valuable and cost-effective option for certain seizure types, particularly in resource-limited settings or for neonatal seizures.

• Levetiracetam (Keppra)
• Valproic acid (Depakote)
• Lamotrigine (Lamictal)
• Carbamazepine (Tegretol)
• Phenytoin (Dilantin)
• Topiramate (Topamax)
• Oxcarbazepine (Trileptal)
• Benzodiazepines (e.g., clonazepam, lorazepam) for acute seizure management or sedation.

If your symptoms or health issues persist or worsen, it is essential to contact your doctor promptly. To ensure safe and effective treatment, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet; consult your pharmacist for more information. If you have any questions or concerns about this medication, discuss them with your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek emergency medical attention. Be prepared to provide details about the overdose, including the medication taken, the amount, and the time it occurred.