Phenobarbital 32.4mg Tablets
WARNING: The use of this drug along with opioid drugs may lead to severe side effects. This includes feeling very sleepy, slow or trouble breathing, passing out, and death. Opioid drugs include drugs like codeine, oxycodone, and morphine. Opioid drugs are used to treat pain and some are used to treat cough. If you have questions, talk with the doctor.If you are taking this drug with an opioid drug, get medical help right away if you feel very sleepy or dizzy; if you have slow, shallow, or trouble breathing; or if you pass out. Caregivers or others need to get medical help right away if the patient does not respond, does not answer or react like normal, or will not wake up. Using this drug for reasons that are not approved may increase the risk for drug use disorder. Misuse or abuse of this drug can lead to overdose or death, especially if used with certain other drugs, alcohol, or street drugs. Get medical help right away if you have changes in mood or behavior, suicidal thoughts or actions, seizures, or trouble breathing. @ COMMON USES: It is used to help control certain kinds of seizures.It is used to treat sleep problems.It may be given to you for other reasons. Talk with the doctor.
Drug Class
Anticonvulsant, Sedative-Hypnotic
Pharmacologic Class
Barbiturate, GABA-A receptor modulator
Pregnancy Category
Category D
FDA Approved
Jan 1970
DEA Schedule
Schedule IV
Overview
What is this medicine?
Phenobarbital is a medication that works on your brain to calm overactive nerve signals. It's primarily used to prevent seizures (epilepsy) and can also be used for short-term sedation or to help with sleep. Because it can make you drowsy, it's often taken at bedtime.
How to Use This Medicine
Taking Your Medication
To use this medication correctly, follow your doctor's instructions and read all the information provided. Take your medication as directed, with or without food. If you experience stomach upset, taking it with food may help.
Storing and Disposing of Your Medication
Keep your medication at room temperature, away from light and moisture. Store it in a dry place, avoiding the bathroom. Make sure to keep the lid tightly closed. To prevent accidental ingestion, store your medication in a secure location where children and pets cannot access it. Consider using a locked box or area to keep your medication safe. Keep all medications out of reach of pets.
Missing a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for a missed one.
To use this medication correctly, follow your doctor's instructions and read all the information provided. Take your medication as directed, with or without food. If you experience stomach upset, taking it with food may help.
Storing and Disposing of Your Medication
Keep your medication at room temperature, away from light and moisture. Store it in a dry place, avoiding the bathroom. Make sure to keep the lid tightly closed. To prevent accidental ingestion, store your medication in a secure location where children and pets cannot access it. Consider using a locked box or area to keep your medication safe. Keep all medications out of reach of pets.
Missing a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for a missed one.
Lifestyle & Tips
- Avoid alcohol and other CNS depressants (e.g., sleeping pills, anxiety medications) as they can increase drowsiness and breathing problems.
- Do not drive or operate heavy machinery until you know how this medication affects you.
- Take the medication exactly as prescribed; do not stop suddenly without consulting your doctor, as this can cause withdrawal seizures.
- Maintain good oral hygiene and regular dental check-ups.
- Consider vitamin D and calcium supplementation, especially with long-term use, to prevent bone thinning.
- Use reliable birth control methods if you are a woman of childbearing potential, as phenobarbital can reduce the effectiveness of oral contraceptives and cause birth defects.
Available Forms & Alternatives
Available Strengths:
- Phenobarbital Sod 65mg/ml Inj, 1ml
- Phenobarbital 97.2mg Tablets
- Phenobarbital 64.8mg Tablets
- Phenobarbital 32.4mg Tablets
- Phenobarbital 16.2mg Tablets
- Phenobarb 130mg/ml Inj, 1ml
- Phenobarbital 100mg Tablets
- Phenobarbital 60mg Tablets
- Phenobarbital 60mg Tablets
- Phenobarbital 15mg Tablets
- Phenobarbital 16.2mg Tablets
- Phenobarbital 32.4mg Tablets
- Phenobarbital 64.8mg Tablets
- Phenobarbital 20mg/5ml Solution
- Phenobarbital 30mg Tablets
- Phenobarbital 97.2mg Tablets
- Phenobarbital 15mg Tablets
Dosing & Administration
Adult Dosing
Standard Dose:
Epilepsy: 60-200 mg/day orally, usually given once daily at bedtime or in divided doses. Sedation: 30-120 mg/day orally in 2-3 divided doses.
Dose Range:
30 - 200 mg
Condition-Specific Dosing:
epilepsy:
60-200 mg/day, adjusted to achieve therapeutic serum levels (15-40 mcg/mL)
sedation:
30-120 mg/day in 2-3 divided doses
insomnia:
100-320 mg at bedtime (short-term use only)
Pediatric Dosing
Neonatal:
Loading dose: 15-20 mg/kg IV. Maintenance: 3-4 mg/kg/day orally or IV, divided every 12-24 hours. (For neonatal seizures)
Infant:
Loading dose: 15-20 mg/kg IV. Maintenance: 3-5 mg/kg/day orally or IV, divided every 12-24 hours.
Child:
Loading dose: 15-20 mg/kg IV. Maintenance: 3-6 mg/kg/day orally or IV, divided every 12-24 hours.
Adolescent:
Initial: 1-3 mg/kg/day orally or IV, adjusted to 60-200 mg/day based on response and serum levels.
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment, monitor for increased sedation.
Moderate:
Consider lower initial doses and monitor serum levels closely.
Severe:
Reduce dose by 25-50%; monitor serum levels closely. Avoid if possible.
Dialysis:
Hemodialysis can remove phenobarbital; supplemental dose may be needed post-dialysis. Peritoneal dialysis removes negligible amounts.
Hepatic Impairment:
Mild:
No specific adjustment, monitor for increased sedation.
Moderate:
Reduce dose by 25-50%; monitor serum levels closely. Avoid if possible.
Severe:
Contraindicated or significantly reduced dose (up to 75% reduction); monitor serum levels closely. Avoid if possible.
Confidence:
Medium
Pharmacology
Mechanism of Action
Phenobarbital is a barbiturate that acts as a non-selective central nervous system (CNS) depressant. Its primary mechanism of action involves binding to a distinct site on the GABA-A receptor complex, enhancing the inhibitory effects of GABA by prolonging the duration of chloride channel opening. This leads to hyperpolarization of the neuronal membrane, decreasing neuronal excitability and raising the seizure threshold. It also inhibits excitatory neurotransmitter release and may have direct effects on voltage-gated ion channels.
Pharmacokinetics
Absorption:
Bioavailability:
80-100%
Tmax:
2-18 hours (oral)
FoodEffect:
Food may slightly delay absorption but does not significantly affect the extent of absorption.
Distribution:
Vd:
0.5-1 L/kg
ProteinBinding:
20-45%
CnssPenetration:
Yes (readily crosses blood-brain barrier)
Elimination:
HalfLife:
50-120 hours (adults), 20-70 hours (children), 100-500 hours (neonates)
Clearance:
0.003-0.007 L/kg/hr
ExcretionRoute:
Renal (unchanged drug and metabolites)
Unchanged:
25-50%
Pharmacodynamics
OnsetOfAction:
Oral: 30-60 minutes; IV: <5 minutes
PeakEffect:
Oral: 8-12 hours; IV: 30 minutes
DurationOfAction:
6-12 hours (sedative effects), prolonged for anticonvulsant effects due to long half-life
Safety & Warnings
Side Effects
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 or hives
+ Itching or red, swollen, blistered, or peeling skin (with or without fever)
+ Wheezing or tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Confusion
Balance problems
Muscle spasms
Bad dreams
Restlessness
Hallucinations (seeing or hearing things that are not there)
Shortness of breath
Slow heartbeat
Feeling extremely tired or weak
Severe dizziness or fainting
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 Effects
In rare cases, people taking seizure medications like this one may experience severe and potentially deadly 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
+ Vomiting
+ 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:
Dizziness or drowsiness
Headache
Upset stomach or vomiting
Constipation
Feeling nervous or 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.
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 or hives
+ Itching or red, swollen, blistered, or peeling skin (with or without fever)
+ Wheezing or tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Confusion
Balance problems
Muscle spasms
Bad dreams
Restlessness
Hallucinations (seeing or hearing things that are not there)
Shortness of breath
Slow heartbeat
Feeling extremely tired or weak
Severe dizziness or fainting
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 Effects
In rare cases, people taking seizure medications like this one may experience severe and potentially deadly 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
+ Vomiting
+ 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:
Dizziness or drowsiness
Headache
Upset stomach or vomiting
Constipation
Feeling nervous or 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.
Seek Immediate Medical Attention If You Experience:
- Severe skin rash, blistering, or peeling (could be Stevens-Johnson Syndrome or Toxic Epidermal Necrolysis)
- Yellowing of skin or eyes (jaundice), dark urine, severe stomach pain (signs of liver problems)
- Unusual bleeding or bruising, persistent sore throat, fever, chills (signs of blood problems)
- Extreme drowsiness, confusion, slurred speech, severe dizziness, unsteadiness (signs of toxicity)
- Difficulty breathing or shallow breathing
- Thoughts of self-harm or suicide, new or worsening depression or anxiety
- Swelling of the face, lips, tongue, or throat (allergic reaction)
Before Using This Medicine
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
+ Heart problems, 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)
+ A very narrow heart valve (aortic stenosis)
If you have recently had a heart attack
If you are taking any medications that can cause abnormal heart rhythms, specifically a prolonged QT interval. Many drugs can cause this condition, so ask 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 dose of any medication without consulting your doctor first.
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
+ Heart problems, 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)
+ A very narrow heart valve (aortic stenosis)
If you have recently had a heart attack
If you are taking any medications that can cause abnormal heart rhythms, specifically a prolonged QT interval. Many drugs can cause this condition, so ask 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 dose of any medication without consulting your doctor first.
Precautions & Cautions
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 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 this medication affects you, avoid driving and engaging in 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 this 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 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 the 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.
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 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 this medication affects you, avoid driving and engaging in 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 this 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 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 the 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.
Overdose Information
Overdose Symptoms:
- Severe drowsiness or coma
- Slurred speech
- Confusion
- Ataxia (loss of coordination)
- Nystagmus (involuntary eye movements)
- Hypotension (low blood pressure)
- Hypothermia (low body temperature)
- Respiratory depression (slow, shallow breathing)
- Shock
- Kidney failure
What to Do:
Seek immediate medical attention. Call 911 or Poison Control at 1-800-222-1222. Treatment may involve supportive care, activated charcoal, gastric lavage, and in severe cases, hemodialysis or hemoperfusion.
Drug Interactions
Contraindicated Interactions
- Porphyria (acute intermittent porphyria)
- Severe respiratory depression
- Severe hepatic impairment
Major Interactions
- Other CNS depressants (e.g., alcohol, opioids, benzodiazepines, tricyclic antidepressants, antihistamines): Increased sedation, respiratory depression.
- Oral contraceptives: Decreased efficacy of contraceptives due to CYP induction.
- Warfarin: Decreased anticoagulant effect due to CYP induction.
- Corticosteroids: Decreased corticosteroid effect due to CYP induction.
- Doxycycline: Decreased doxycycline levels due to CYP induction.
- Griseofulvin: Decreased griseofulvin levels due to CYP induction.
- Lamotrigine, Tiagabine, Zonisamide, Topiramate, Valproic Acid, Carbamazepine, Phenytoin: Altered levels of phenobarbital or co-administered AEDs.
- Ritonavir, Lopinavir/Ritonavir: Decreased antiretroviral levels.
- Chloramphenicol: Increased phenobarbital levels.
- MAO inhibitors: Increased phenobarbital effects.
Moderate Interactions
- Acetaminophen: Increased risk of hepatotoxicity with chronic phenobarbital use.
- Digoxin: Decreased digoxin levels.
- Quinidine: Decreased quinidine levels.
- Theophylline: Decreased theophylline levels.
- Verapamil: Decreased verapamil levels.
- Folic acid: May decrease phenobarbital levels; phenobarbital may cause folate deficiency.
Minor Interactions
- Vitamin D: May increase vitamin D metabolism, leading to deficiency.
- Calcium supplements: May be needed due to altered vitamin D metabolism.
Monitoring
Baseline Monitoring
Complete Blood Count (CBC) with differential
Rationale: To establish baseline and monitor for blood dyscrasias (e.g., megaloblastic anemia, thrombocytopenia, leukopenia).
Timing: Prior to initiation
Liver Function Tests (LFTs) - AST, ALT, ALP, Bilirubin
Rationale: To establish baseline and monitor for hepatotoxicity.
Timing: Prior to initiation
Renal Function Tests (BUN, Creatinine)
Rationale: To establish baseline and guide dosing in renal impairment.
Timing: Prior to initiation
Serum Phenobarbital Level
Rationale: To establish baseline and guide initial dosing, especially in complex cases.
Timing: Prior to initiation (optional, but useful)
Routine Monitoring
Serum Phenobarbital Level
Frequency: Initially after 2-4 weeks (to reach steady state), then every 3-6 months or as clinically indicated (e.g., dose change, suspected toxicity, loss of seizure control).
Target: 15-40 mcg/mL (therapeutic range for epilepsy)
Action Threshold: Levels >40 mcg/mL often associated with toxicity (sedation, nystagmus, ataxia); levels <15 mcg/mL may indicate subtherapeutic dosing.
Complete Blood Count (CBC) with differential
Frequency: Every 6-12 months, or if symptoms of blood dyscrasias occur.
Target: Within normal limits
Action Threshold: Significant drops in cell counts (e.g., anemia, leukopenia, thrombocytopenia) warrant investigation and potential drug discontinuation.
Liver Function Tests (LFTs)
Frequency: Every 6-12 months, or if symptoms of hepatic dysfunction occur.
Target: Within normal limits
Action Threshold: Significant elevations (e.g., >3x upper limit of normal) warrant investigation and potential drug discontinuation.
Vitamin D and Calcium levels
Frequency: Annually for long-term therapy, especially in children and elderly.
Target: Within normal limits
Action Threshold: Deficiency may require supplementation.
Symptom Monitoring
- Excessive sedation
- Drowsiness
- Lethargy
- Ataxia (uncoordinated movements)
- Nystagmus (involuntary eye movements)
- Cognitive impairment (memory, concentration difficulties)
- Irritability or paradoxical hyperactivity (especially in children)
- Skin rash (Stevens-Johnson Syndrome, Toxic Epidermal Necrolysis)
- Signs of liver dysfunction (jaundice, dark urine, abdominal pain)
- Signs of blood dyscrasias (unusual bruising, bleeding, fatigue, fever)
- Changes in seizure frequency or type
- Mood changes, suicidal ideation
Special Patient Groups
Pregnancy
Category D. Phenobarbital is a known human teratogen. It is associated with an increased risk of major congenital malformations (e.g., neural tube defects, cardiac defects, cleft lip/palate) and neonatal withdrawal syndrome. Use only if the potential benefit outweighs the significant risk to the fetus. Folic acid supplementation is recommended for women of childbearing potential.
Trimester-Specific Risks:
First Trimester:
Highest risk for major congenital malformations (e.g., neural tube defects, cardiac defects, oral clefts).
Second Trimester:
Continued risk of malformations, though lower than first trimester. Potential for neurodevelopmental effects.
Third Trimester:
Risk of neonatal withdrawal syndrome (irritability, tremors, hypertonia, feeding difficulties) and hemorrhagic disease of the newborn (due to vitamin K deficiency).
Lactation
L4 (Possibly Hazardous). Phenobarbital is excreted into breast milk and can cause significant sedation, poor feeding, and withdrawal symptoms in the infant upon discontinuation of breastfeeding. Monitor the infant closely for drowsiness, poor weight gain, and respiratory depression. Breastfeeding is generally not recommended, or only with extreme caution and close infant monitoring.
Infant Risk:
High (sedation, poor feeding, withdrawal, respiratory depression)
Pediatric Use
Children, especially younger ones, may experience paradoxical hyperactivity, irritability, and cognitive impairment. Close monitoring of serum levels and clinical response is essential. Long-term use can affect bone health (rickets/osteomalacia) and folate levels.
Geriatric Use
Elderly patients are more sensitive to the CNS depressant effects (sedation, ataxia, confusion) and may require lower doses. Increased risk of falls. Monitor renal and hepatic function closely.
Clinical Information
Clinical Pearls
- Phenobarbital has a very long half-life, meaning it takes a long time to reach steady-state levels (weeks) and to be eliminated from the body. This makes dose adjustments slow and requires patience.
- Therapeutic drug monitoring (TDM) of serum phenobarbital levels is crucial for optimizing efficacy and minimizing toxicity, especially given its narrow therapeutic index.
- Due to its potent enzyme-inducing properties, phenobarbital has numerous significant drug-drug interactions, particularly with oral contraceptives, warfarin, and other antiepileptic drugs.
- Abrupt discontinuation can precipitate severe withdrawal symptoms, including status epilepticus, especially in patients treated for epilepsy. Taper slowly over weeks to months.
- Despite its older age, phenobarbital remains a valuable, cost-effective option for certain types of seizures, particularly in neonates and in resource-limited settings.
- Patients on long-term phenobarbital therapy should be monitored for bone health (vitamin D and calcium levels) and folate deficiency.
Alternative Therapies
- Other antiepileptic drugs (e.g., Levetiracetam, Valproic Acid, Carbamazepine, Phenytoin, Lamotrigine, Topiramate)
- Benzodiazepines (for acute seizure management or short-term sedation, e.g., Lorazepam, Diazepam)
- Non-benzodiazepine hypnotics (for insomnia, e.g., Zolpidem, Eszopiclone)
Cost & Coverage
Average Cost:
$10 - $50 per 30 tablets (32.4mg)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or 2 (Generic)
General Drug Facts
If your symptoms or health issues persist or worsen, it is essential to contact your doctor promptly. To ensure safe use, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so it's a good idea to check with your pharmacist for more information. If you have any questions or concerns about this medication, don't hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek medical attention. When seeking help, be prepared to provide details about the medication taken, the amount, and the time it happened.