Phenobarbital 64.8mg Tablets

Phenobarbital is a barbiturate that produces nonselective depression of the central nervous system (CNS). It binds to the GABA-A receptor complex at a distinct site from benzodiazepines, enhancing the inhibitory effects of GABA by increasing the duration of chloride ion channel opening. This leads to neuronal hyperpolarization and reduced neuronal excitability, thereby raising the seizure threshold and producing sedative, hypnotic, and anticonvulsant effects.

Urgent Side Effects: Seek Medical Help Right Away

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

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

Severe and Potentially Life-Threatening Side Effects

In rare cases, people taking seizure medications like this one may experience severe and potentially life-threatening side effects. Contact your doctor right away if you notice:

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

Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to contact your doctor or seek medical help if you notice any of the following:

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

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. Be sure to describe the allergic reaction and its symptoms.
Certain health conditions, such as liver disease or breathing difficulties, like shortness of breath.
A history of porphyria, a rare genetic disorder.
Heart-related 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 condition characterized by a very narrow heart valve
Recent heart attack
Use of medications that can cause abnormal heart rhythms, specifically prolonged QT interval. There are many medications that can have this effect, so it is crucial to consult your doctor or pharmacist if you are unsure.

This list is not exhaustive, and it is vital to discuss all your medications (prescription, over-the-counter, natural products, and vitamins) and health conditions with your doctor and pharmacist. They will help determine whether it is safe to take this medication in conjunction with your other medications and health conditions. Never start, stop, or adjust the dosage of any medication without consulting your doctor first.

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, you may develop tolerance, requiring higher doses to achieve the same effect. If you notice the medication is not working as well as it previously did, 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. Until you know how the medication affects you, avoid driving and other activities that require alertness. Additionally, avoid consuming alcohol while taking this medication.

Interactions with Other Substances
Before using marijuana, cannabis, or prescription or over-the-counter medications that may cause drowsiness, consult your doctor. These substances can interact with your medication and increase the risk of adverse effects.

Suicidal Thoughts and Actions
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 behavior. If you experience new or worsening symptoms such as depression, anxiety, restlessness, 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 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.
If you are pregnant or become pregnant while taking this medication, contact your doctor immediately, as the medication may harm the unborn baby.
Taking this medication during the third trimester of pregnancy may lead to side effects or withdrawal in the newborn.
If you are breastfeeding, discuss the risks to your baby with your doctor.

Seizure-Specific Warnings
If your seizures change or worsen after starting this medication, consult your doctor to discuss the best course of action.

• Porphyria (acute intermittent porphyria)
• Severe respiratory depression
• Severe hepatic impairment
• Known hypersensitivity to barbiturates

• Alcohol (additive CNS depression)
• Other CNS depressants (e.g., benzodiazepines, opioids, tricyclic antidepressants, antihistamines) - additive CNS depression
• Oral contraceptives (decreased efficacy due to enzyme induction)
• Warfarin (decreased anticoagulant effect due to enzyme induction)
• Corticosteroids (decreased efficacy due to enzyme induction)
• Doxycycline (decreased efficacy due to enzyme induction)
• Griseofulvin (decreased efficacy due to enzyme induction)
• Lamotrigine (decreased lamotrigine levels)
• Tiagabine (decreased tiagabine levels)
• Valproic acid (increased phenobarbital levels, decreased valproic acid levels)
• Felbamate (increased phenobarbital levels)
• Vigabatrin (decreased phenobarbital levels)
• Methadone (decreased methadone levels, risk of withdrawal)
• Antiretrovirals (e.g., protease inhibitors, NNRTIs - decreased levels)
• Cyclosporine, Tacrolimus (decreased levels)
• Quetiapine (decreased quetiapine levels)
• Rifampin (decreased phenobarbital levels)

• Acetaminophen (increased risk of hepatotoxicity with chronic use)
• Carbamazepine (decreased carbamazepine levels, increased phenobarbital levels)
• Phenytoin (variable effect on levels of both drugs)
• Topiramate (decreased topiramate levels)
• Zonisamide (decreased zonisamide levels)
• Folic acid (may decrease phenobarbital levels)
• Vitamin D (may increase vitamin D metabolism)

• Ginkgo biloba (may reduce seizure threshold)
• St. John's Wort (enzyme induction, decreased phenobarbital levels)

• Excessive sedation
• Drowsiness
• Lethargy
• Ataxia (impaired coordination)
• Nystagmus (involuntary eye movements)
• Slurred speech
• Confusion
• Irritability or hyperactivity (paradoxical effect, especially in children)
• Rash (including severe cutaneous adverse reactions like SJS/TEN)
• Fever
• Sore throat
• Unusual bleeding or bruising
• Yellowing of skin or eyes (jaundice)
• Dark urine
• Abdominal pain
• Changes in mood or behavior (including suicidal ideation)

Phenobarbital is classified as Pregnancy Category D. It is associated with an increased risk of major congenital malformations, including neural tube defects, cardiac malformations, and oral clefts. It can also cause a fetal barbiturate syndrome (facial dysmorphism, growth retardation, developmental delay) and neonatal withdrawal symptoms (irritability, tremors, hypertonia, feeding difficulties) if used during the third trimester. Use only if the potential benefit outweighs the potential risk to the fetus, and discuss risks thoroughly with the patient.

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. Use with caution, monitor the infant closely for sedation, and consider alternative agents if possible.

Children, especially younger children, may exhibit paradoxical hyperactivity or irritability. Neonates and infants have significantly longer half-lives due to immature hepatic metabolism and renal excretion, requiring careful dose titration and monitoring. Higher doses per kg may be needed in older children due to faster metabolism compared to adults.

Elderly patients may be more sensitive to the sedative and CNS depressant effects of phenobarbital, including an increased risk of falls, confusion, and respiratory depression. Lower initial doses and slower titration are recommended. Monitor closely for adverse effects and drug interactions.

• Phenobarbital has a very long half-life, allowing for once-daily dosing for epilepsy, but also leading to slow attainment of steady-state levels (weeks) and slow elimination upon discontinuation.
• Due to its potent enzyme-inducing properties, phenobarbital can significantly reduce the efficacy of many co-administered drugs, including oral contraceptives, warfarin, and other antiepileptics. Careful monitoring and dose adjustments of concomitant medications are crucial.
• Abrupt discontinuation of phenobarbital, especially after prolonged use, can precipitate severe withdrawal symptoms, including status epilepticus, delirium, and hallucinations. Tapering the dose gradually over weeks to months is essential.
• Therapeutic drug monitoring (TDM) of phenobarbital levels is important due to its narrow therapeutic index and significant inter-individual variability in metabolism and clearance.
• Phenobarbital is a controlled substance (Schedule IV) with a risk of physical and psychological dependence. Prescribe with caution and monitor for signs of abuse or dependence.
• Despite being an older drug, phenobarbital remains a highly effective and inexpensive antiepileptic, particularly for generalized tonic-clonic and partial seizures, and neonatal seizures.

• Other Antiepileptic Drugs (AEDs): Carbamazepine, Valproic Acid, Phenytoin, Lamotrigine, Levetiracetam, Topiramate, Oxcarbazepine, Zonisamide, Gabapentin, Pregabalin.
• For Sedation/Insomnia: Benzodiazepines (e.g., lorazepam, temazepam), Z-drugs (e.g., zolpidem), Antihistamines (e.g., diphenhydramine), Melatonin, Ramelteon.

If your symptoms or health issues persist or worsen, it is essential to contact your doctor promptly. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so it is a good idea to consult with your pharmacist. If you have any questions or concerns about this medication, do not hesitate to 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. When seeking help, be prepared to provide detailed information about the overdose, including the medication taken, the amount, and the time it occurred.