Phenobarbital 60mg 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
Pregnancy Category
Category D
FDA Approved
Jan 1970
DEA Schedule
Schedule IV
Overview
What is this medicine?
Phenobarbital is a medication used to control seizures (epilepsy) and to help with anxiety or trouble sleeping. It works by calming the brain and nervous system. It belongs to a class of drugs called barbiturates.
How to Use This Medicine
Taking Your Medication
To use this medication correctly, follow your doctor's instructions and read all the information provided. You can take this medication with or without food. If it causes 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, such as a closet or drawer, and avoid storing it in 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. You can take this medication with or without food. If it causes 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, such as a closet or drawer, and avoid storing it in 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
- Do not stop taking phenobarbital suddenly, as this can cause severe withdrawal symptoms or seizures. Always consult your doctor before changing your dose.
- Avoid alcohol and other medications that cause drowsiness (e.g., cold medicines, pain relievers, other sedatives) as they can increase the sedative effects of phenobarbital.
- Do not drive or operate heavy machinery until you know how phenobarbital affects you, as it can cause drowsiness, dizziness, and impaired coordination.
- If you are taking phenobarbital for seizures, carry identification stating your condition and medication.
- Long-term use may require vitamin D and folic acid supplementation; discuss with your doctor.
- Women of childbearing potential should use effective contraception, as phenobarbital can reduce the effectiveness of hormonal birth control.
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:
Initial: 60-100 mg/day, adjusted based on clinical response and plasma levels. Maintenance: 60-200 mg/day.
sedation:
30-120 mg/day in 2-3 divided doses.
Pediatric Dosing
Neonatal:
Loading dose: 15-20 mg/kg IV. Maintenance: 3-4 mg/kg/day orally or IV in 1-2 divided doses.
Infant:
Loading dose: 15-20 mg/kg IV. Maintenance: 3-5 mg/kg/day orally or IV in 1-2 divided doses.
Child:
Loading dose: 15-20 mg/kg IV. Maintenance: 3-6 mg/kg/day orally or IV in 1-2 divided doses.
Adolescent:
Epilepsy: 1-6 mg/kg/day orally in 1-2 divided doses, or adult dosing (60-200 mg/day).
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment, monitor for increased sedation.
Moderate:
Consider dose reduction by 25-50%, monitor plasma levels and clinical response.
Severe:
Consider dose reduction by 50-75%, monitor plasma levels and clinical response closely.
Dialysis:
Hemodialysis removes phenobarbital; supplemental dose may be needed post-dialysis. Peritoneal dialysis removes phenobarbital to a lesser extent.
Hepatic Impairment:
Mild:
Monitor for increased sedation and toxicity.
Moderate:
Consider dose reduction by 25-50%, monitor plasma levels and clinical response.
Severe:
Contraindicated or significant dose reduction (up to 75%) required, monitor plasma levels and clinical response closely.
Pharmacology
Mechanism of Action
Phenobarbital is a barbiturate that produces nonselective depression of the central nervous system (CNS). It binds to a distinct site on the GABA-A receptor complex, enhancing the inhibitory effects of GABA by increasing the duration of chloride channel opening. This leads to hyperpolarization of the neuronal membrane, decreasing neuronal excitability and seizure propagation. It also inhibits excitatory neurotransmission.
Pharmacokinetics
Absorption:
Bioavailability:
80-100%
Tmax:
Oral: 8-12 hours (range 2-18 hours)
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
Elimination:
HalfLife:
Adults: 53-118 hours (average 79 hours); Children: 37-73 hours; Neonates: 100-500 hours
Clearance:
Adults: 3-12 mL/kg/hr
ExcretionRoute:
Renal (25-50% as unchanged drug, remainder as 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); Anticonvulsant effects persist longer 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
+ 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
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 Side Effects
In rare cases, people taking seizure medications like this one may experience severe and potentially deadly 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
+ Changes 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 experience any side effects that bother you or do not go away, contact your doctor for medical advice. 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
+ 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
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 Side Effects
In rare cases, people taking seizure medications like this one may experience severe and potentially deadly 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
+ Changes 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 experience any side effects that bother you or do not go away, contact your doctor for medical advice. 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 a sign of a serious skin reaction like Stevens-Johnson syndrome)
- Yellowing of the skin or eyes (jaundice), dark urine, or persistent nausea/vomiting (signs of liver problems)
- Unusual bleeding or bruising, persistent sore throat, or fever (signs of blood problems)
- Extreme drowsiness, confusion, slurred speech, or difficulty breathing (signs of overdose or excessive sedation)
- Paradoxical excitement, irritability, or hyperactivity (especially in children)
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. 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 with your existing health conditions and medications. Never start, stop, or adjust the dosage 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. 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 with your existing health conditions and medications. Never start, stop, or adjust the dosage 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, that you are using this drug.
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 this medication, consult your doctor and follow their instructions carefully. Abruptly lowering the dose or stopping this medication can lead to withdrawal, which can be life-threatening. Seek immediate medical attention if you experience any adverse effects.
Tolerance
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 that 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, other forms of cannabis, or prescription or over-the-counter medications that may cause drowsiness, consult your doctor.
Suicidal Thoughts and Actions
Like other medications used to treat seizures, this drug 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 medical attention right away.
Special Populations
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, inform your doctor immediately. Taking this medication during 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 as needed.
When taking this medication, it is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are using this drug.
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 this medication, consult your doctor and follow their instructions carefully. Abruptly lowering the dose or stopping this medication can lead to withdrawal, which can be life-threatening. Seek immediate medical attention if you experience any adverse effects.
Tolerance
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 that 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, other forms of cannabis, or prescription or over-the-counter medications that may cause drowsiness, consult your doctor.
Suicidal Thoughts and Actions
Like other medications used to treat seizures, this drug 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 medical attention right away.
Special Populations
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, inform your doctor immediately. Taking this medication during 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 as needed.
Overdose Information
Overdose Symptoms:
- Severe drowsiness or coma
- Slurred speech
- Ataxia (loss of coordination)
- Nystagmus (involuntary eye movements)
- Hypotension (low blood pressure)
- Hypothermia (low body temperature)
- Respiratory depression (slow, shallow breathing)
- Pulmonary edema
- Renal failure
- Shock
What to Do:
Seek immediate medical attention. Call 911 or your local emergency number. For poison control, call 1-800-222-1222. Treatment involves supportive care, maintaining airway and breathing, gastric lavage, activated charcoal, and potentially hemodialysis for severe cases.
Drug Interactions
Contraindicated Interactions
- Porphyria (acute intermittent porphyria, variegate porphyria, hereditary coproporphyria)
- Severe respiratory depression
- Severe hepatic impairment
Major Interactions
- Other CNS depressants (e.g., alcohol, opioids, benzodiazepines, tricyclic antidepressants, antihistamines): Increased CNS depression, respiratory depression, hypotension.
- Valproic acid, valproate semisodium: Increased phenobarbital levels due to inhibition of metabolism.
- Felbamate: Increased phenobarbital levels.
- Oral contraceptives: Decreased efficacy of oral 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: Decreased lamotrigine levels due to CYP induction.
- Tiagabine: Decreased tiagabine levels due to CYP induction.
- Topiramate: Decreased topiramate levels due to CYP induction.
- Zonisamide: Decreased zonisamide levels due to CYP induction.
- Immunosuppressants (e.g., cyclosporine, tacrolimus): Decreased immunosuppressant levels due to CYP induction.
- HIV protease inhibitors (e.g., ritonavir, saquinavir): Decreased protease inhibitor levels due to CYP induction.
- Calcium channel blockers (e.g., verapamil, nifedipine): Decreased calcium channel blocker levels due to CYP induction.
- Digoxin: Decreased digoxin levels due to CYP induction.
Moderate Interactions
- Acetaminophen: Increased risk of hepatotoxicity with chronic phenobarbital use.
- Carbamazepine: Decreased phenobarbital levels and increased carbamazepine epoxide levels.
- Phenytoin: Variable effects on both drug levels; monitor closely.
- Rifampin: Decreased phenobarbital levels due to CYP induction.
- St. John's Wort: Decreased phenobarbital levels due to CYP induction.
- Thyroid hormones: Decreased thyroid hormone levels due to increased metabolism.
Minor Interactions
- Folic acid: May decrease phenobarbital levels; phenobarbital may decrease folate levels.
- Vitamin D: May decrease vitamin D levels due to increased metabolism.
Monitoring
Baseline Monitoring
Complete Blood Count (CBC)
Rationale: To establish baseline and monitor for potential hematologic abnormalities (e.g., megaloblastic anemia, agranulocytosis) associated with long-term barbiturate use.
Timing: Prior to initiation of therapy.
Liver Function Tests (LFTs)
Rationale: To establish baseline and monitor for potential hepatotoxicity, as phenobarbital is metabolized in the liver.
Timing: Prior to initiation of therapy.
Renal Function Tests (BUN, Creatinine)
Rationale: To establish baseline and assess renal clearance, as a significant portion of phenobarbital is renally excreted.
Timing: Prior to initiation of therapy.
Phenobarbital Plasma Levels
Rationale: To establish baseline and guide initial dosing, especially in complex cases or when rapid therapeutic levels are desired.
Timing: Prior to initiation or after loading dose.
Routine Monitoring
Phenobarbital Plasma Levels
Frequency: Initially after steady-state (2-3 weeks), then every 6-12 months or as clinically indicated (e.g., dose change, suspected toxicity, seizure recurrence).
Target: 15-40 mcg/mL (therapeutic range for epilepsy)
Action Threshold: Levels >40 mcg/mL may indicate toxicity; levels <15 mcg/mL may indicate subtherapeutic dosing. Adjust dose based on clinical response and levels.
Liver Function Tests (LFTs)
Frequency: Every 6-12 months or as clinically indicated (e.g., symptoms of liver dysfunction).
Target: Within normal limits
Action Threshold: Significant elevation (e.g., >3x ULN) may require dose reduction or discontinuation.
Complete Blood Count (CBC)
Frequency: Every 6-12 months or as clinically indicated (e.g., unexplained fever, bruising, fatigue).
Target: Within normal limits
Action Threshold: Significant abnormalities (e.g., severe leukopenia, thrombocytopenia, anemia) may require investigation and potential discontinuation.
Clinical Assessment (Sedation, Ataxia, Cognitive Function, Mood)
Frequency: At every clinical visit.
Target: Optimal seizure control with minimal side effects.
Action Threshold: Excessive sedation, ataxia, nystagmus, cognitive impairment, or paradoxical hyperactivity (especially in children) may indicate toxicity or need for dose adjustment.
Symptom Monitoring
- Excessive drowsiness or sedation
- Dizziness
- Ataxia (impaired coordination)
- Nystagmus (involuntary eye movements)
- Confusion or disorientation
- Irritability or paradoxical hyperactivity (especially in children)
- Skin rash (Stevens-Johnson syndrome, toxic epidermal necrolysis)
- Fever, sore throat, or unusual bruising/bleeding (signs of blood dyscrasias)
- Yellowing of skin or eyes, dark urine, abdominal pain (signs of liver dysfunction)
- Respiratory depression
Special Patient Groups
Pregnancy
Phenobarbital is classified as Pregnancy Category D, indicating positive evidence of human fetal risk. It is associated with an increased risk of congenital malformations, including cardiac defects, cleft lip/palate, and neural tube defects. It can also cause neonatal withdrawal syndrome and hemorrhagic disease of the newborn.
Trimester-Specific Risks:
First Trimester:
Increased risk of major congenital malformations (e.g., cardiac defects, cleft lip/palate, neural tube defects).
Second Trimester:
Continued risk of developmental abnormalities; potential for growth restriction.
Third Trimester:
Risk of neonatal withdrawal syndrome (irritability, tremors, hypertonia, feeding difficulties) and hemorrhagic disease of the newborn (due to vitamin K deficiency).
Lactation
Phenobarbital is excreted into breast milk and is classified as L3 (Moderate Risk). It can cause sedation, poor feeding, and withdrawal symptoms in breastfed infants. Monitoring the infant for drowsiness, poor weight gain, and developmental milestones is crucial. Use with caution, or consider alternative medications.
Infant Risk:
Moderate risk. Potential for infant sedation, lethargy, poor feeding, and withdrawal symptoms upon discontinuation of breastfeeding.
Pediatric Use
Children, especially younger ones, may experience paradoxical hyperactivity or irritability instead of sedation. Close monitoring for behavioral changes is essential. Dosing is weight-based. Long-term use may affect bone mineral density and require vitamin D supplementation.
Geriatric Use
Elderly patients are more sensitive to the sedative and CNS depressant effects of phenobarbital. They are at increased risk of falls, confusion, and respiratory depression. Lower initial doses and careful titration are recommended. Monitor renal and hepatic function closely.
Clinical Information
Clinical Pearls
- Phenobarbital has a very long half-life, leading to slow achievement of steady-state (weeks) and slow elimination. This makes dose adjustments challenging and requires patience.
- Therapeutic drug monitoring (TDM) is crucial for phenobarbital to optimize efficacy and minimize toxicity, especially given its narrow therapeutic index.
- Phenobarbital is a potent inducer of multiple CYP450 enzymes and UGT, leading to numerous significant drug-drug interactions, particularly with oral contraceptives, warfarin, and other antiepileptic drugs.
- Abrupt discontinuation can precipitate severe withdrawal symptoms, including status epilepticus. Tapering off phenobarbital should be done gradually over weeks to months.
- Despite its older age, phenobarbital remains a valuable, cost-effective option for certain types of epilepsy, especially in resource-limited settings or for refractory seizures.
- Monitor for signs of serious dermatologic reactions (SJS/TEN), which, though rare, can be life-threatening.
Alternative Therapies
- For epilepsy: Levetiracetam, Valproic acid, Carbamazepine, Phenytoin, Lamotrigine, Topiramate, Oxcarbazepine, Zonisamide, Gabapentin, Pregabalin.
- For sedation/anxiety: Benzodiazepines (e.g., lorazepam, diazepam), Buspirone, Antihistamines (e.g., hydroxyzine), Non-benzodiazepine hypnotics (e.g., zolpidem).
Cost & Coverage
Average Cost:
$10 - $30 per 30 tablets (60mg)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or Tier 2 (preferred generic)
General Drug Facts
If your symptoms or health issues persist or worsen, it's essential to contact your doctor for further guidance. 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 be sure to check with your pharmacist for more details. If you have any questions or concerns about your 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 information about the medication taken, the amount, and the time it happened.