Promethazine 25mg Tablets

Manufacturer ZYDUS PHARMACEUTICALS (USA) Active Ingredient Promethazine Tablets(proe METH a zeen) Pronunciation proe METH a zeen
WARNING: Children:Do not give this drug to a child younger than 2 years of age. It may cause very bad and sometimes deadly breathing problems.Use with care in children 2 years of age and older. Talk with the doctor.Before your child takes this drug, tell the doctor if your child is taking any drugs that can cause breathing problems. There are many drugs that can do this. Ask the doctor or pharmacist if you are not sure. @ COMMON USES: It is used to ease allergy signs.It is used to help motion sickness.It is used to manage pain.It is used to prevent upset stomach and throwing up from surgery.It may be given to you for other reasons. Talk with the doctor.
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Drug Class
Antihistamine, Antiemetic, Sedative
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Pharmacologic Class
Phenothiazine derivative, H1-receptor antagonist
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Pregnancy Category
C
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FDA Approved
Sep 1951
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DEA Schedule
Not Controlled

Overview

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What is this medicine?

Promethazine is an antihistamine that can help relieve allergy symptoms like sneezing and runny nose. It's also used to prevent and treat nausea and vomiting, and to help you relax or sleep before surgery or at bedtime. It works by blocking a natural substance (histamine) that your body makes.
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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, take it with food to help minimize this side effect. If you're using this medication to prevent motion sickness, take it 30 to 60 minutes before traveling.

Storing and Disposing of Your Medication

Store this medication at room temperature, away from light and moisture. Keep it in a dry place, such as a closet or drawer, and avoid storing it in the bathroom. Keep all medications in a safe location, out of the reach of children and pets. When disposing of unused or expired medication, do not flush it down the toilet or pour it down the drain unless instructed to do so by your pharmacist. Instead, check with your pharmacist for guidance on the best disposal method or participate in a drug take-back program in your area.

Missing a Dose

If you take this medication regularly and miss a dose, take it as soon as you remember. However, if it's close to the time for your next dose, skip the missed dose and resume your regular schedule. Do not take two doses at the same time or take extra doses. If you take this medication as needed, follow your doctor's instructions and do not take it more frequently than recommended.
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Lifestyle & Tips

  • Avoid alcohol and other medications that cause drowsiness (e.g., pain relievers, sleeping pills) while taking promethazine, as this can increase sedation and breathing problems.
  • Do not drive or operate heavy machinery until you know how this medication affects you, as it can cause significant drowsiness and dizziness.
  • Avoid prolonged exposure to sunlight or tanning beds, as promethazine can make your skin more sensitive to the sun.
  • Stay hydrated to help with dry mouth, a common side effect.

Dosing & Administration

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Adult Dosing

Standard Dose: For allergy: 25 mg at bedtime or 12.5 mg before meals and at bedtime. For nausea/vomiting: 25 mg initially, then 12.5-25 mg every 4-6 hours as needed. For sedation: 25-50 mg at bedtime or preoperatively. For motion sickness: 25 mg 30-60 minutes before travel, then every 8-12 hours as needed.
Dose Range: 12.5 - 50 mg

Condition-Specific Dosing:

allergy: 12.5-25 mg orally every 4-6 hours or 25 mg at bedtime
nausea_vomiting: 25 mg orally initially, then 12.5-25 mg every 4-6 hours as needed
sedation: 25-50 mg orally at bedtime or preoperatively
motion_sickness: 25 mg orally 30-60 minutes before travel, then 25 mg every 8-12 hours as needed
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Pediatric Dosing

Neonatal: Contraindicated in children younger than 2 years of age due to risk of fatal respiratory depression.
Infant: Contraindicated in children younger than 2 years of age due to risk of fatal respiratory depression.
Child: For allergy/sedation: 0.5 mg/kg/dose orally every 4-6 hours as needed, or 12.5-25 mg at bedtime. Max 50 mg/day. For nausea/vomiting: 0.5 mg/kg/dose orally every 4-6 hours as needed. Max 25 mg/dose. For motion sickness: 12.5-25 mg orally 30-60 minutes before travel, then every 8-12 hours as needed.
Adolescent: Same as adult dosing, generally 12.5-25 mg orally every 4-6 hours as needed.
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Dose Adjustments

Renal Impairment:

Mild: No specific adjustment recommended, use with caution.
Moderate: No specific adjustment recommended, use with caution.
Severe: Use with caution; consider reduced dose or extended interval due to potential for accumulation of metabolites. Monitor for increased sedation.
Dialysis: Not significantly dialyzable. Use with caution; monitor for adverse effects.

Hepatic Impairment:

Mild: Use with caution; monitor for increased sedation and anticholinergic effects.
Moderate: Consider dose reduction (e.g., 50% of usual dose) and extended dosing intervals. Monitor closely for adverse effects.
Severe: Contraindicated or not recommended due to extensive hepatic metabolism and potential for severe adverse effects. Consult specialist.

Pharmacology

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Mechanism of Action

Promethazine is a phenothiazine derivative that acts as a potent, first-generation H1-receptor antagonist. It competitively blocks histamine H1 receptors, thereby preventing the effects of histamine on capillaries, bronchi, and GI smooth muscle. Its antiemetic effects are attributed to its anticholinergic and central antidopaminergic actions on the chemoreceptor trigger zone (CTZ). It also possesses significant anticholinergic, sedative, and alpha-adrenergic blocking properties.
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Pharmacokinetics

Absorption:

Bioavailability: 25-50% (variable due to significant first-pass metabolism)
Tmax: 2-3 hours
FoodEffect: Food may delay absorption but does not significantly affect the extent of absorption.

Distribution:

Vd: 131-177 L/kg
ProteinBinding: 93%
CnssPenetration: Yes (readily crosses blood-brain barrier)

Elimination:

HalfLife: 10-14 hours (range 7-19 hours)
Clearance: Not readily available, but primarily hepatic clearance.
ExcretionRoute: Renal (primarily as inactive metabolites), small amount in feces.
Unchanged: <1% (in urine)
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Pharmacodynamics

OnsetOfAction: 20 minutes (oral)
PeakEffect: 2-3 hours
DurationOfAction: 4-6 hours (up to 12 hours for some effects)

Safety & Warnings

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BLACK BOX WARNING

RESPIRATORY DEPRESSION: Promethazine should not be used in pediatric patients less than 2 years of age because of the potential for fatal respiratory depression. Postmarketing cases of respiratory depression, including fatalities, have been reported with use of promethazine in pediatric patients less than 2 years of age. Caution should be exercised when administering promethazine to pediatric patients 2 years of age and older. Promethazine may impair the mental and/or physical abilities required for the performance of potentially hazardous tasks, such as driving a car or operating machinery. The concomitant use of alcohol or other central nervous system depressants, including opioids, may have an additive effect and should be avoided. TISSUE INJURY: Cases of severe chemical irritation and damage, including gangrene, requiring surgical intervention (including amputation) have been reported with promethazine injection, particularly with intravenous administration. The preferred route of administration is deep intramuscular injection. Subcutaneous injection is contraindicated. Intravenous administration is not recommended. If intravenous administration is necessary, it should be done via a large-bore, patent vein, with the drug diluted and administered slowly.
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Side Effects

Serious Side Effects: Seek Medical Help Immediately

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 medical attention right away:

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
Signs of high or low blood pressure, including:
+ Severe headache
+ Dizziness
+ Passing out
+ Changes in eyesight
Abnormal heart rhythms, such as:
+ Fast or slow heartbeat
Neurological symptoms, including:
+ Trouble controlling body movements
+ Twitching
+ Changes in balance
+ Difficulty swallowing or speaking
+ Shakiness
+ Trouble moving around
+ Stiffness
Confusion or disorientation
Feeling nervous or excitable
Hallucinations (seeing or hearing things that are not there)
Mood changes
Ringing in the ears
Seizures
Unexplained bruising or bleeding
Yellowing of the skin or eyes
* Changes in eyesight

Neuroleptic Malignant Syndrome (NMS): A rare but potentially life-threatening condition called NMS may occur. Seek medical help immediately if you experience:
+ Fever
+ Muscle cramps or stiffness
+ Dizziness
+ Severe headache
+ Confusion
+ Changes in thinking
+ Fast heartbeat
+ Abnormal heartbeat
+ Excessive sweating

Respiratory Problems: This medication may cause severe and potentially life-threatening breathing problems. Seek medical help immediately if you experience:
+ Slow, shallow, or troubled breathing

Low White Blood Cell Count: This medication may increase the risk of infection due to a low white blood cell count. Seek medical help immediately if you experience:
+ Signs of infection, such as:
- Fever
- Chills
- Sore throat

Other Side Effects

Most people do not experience serious side effects, and many side effects are mild and temporary. However, if you experience any of the following side effects, contact your doctor or seek medical attention if they bother you or do not go away:
+ Dizziness
+ Drowsiness
+ Fatigue
+ Weakness
+ Blurred vision
+ Dry mouth
+ Upset stomach or vomiting
+ Trouble sleeping
+ Stuffy nose

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.
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Seek Immediate Medical Attention If You Experience:

  • Severe drowsiness or difficulty waking up
  • Slow or shallow breathing
  • Confusion or hallucinations
  • Uncontrolled muscle movements (tremors, twitching, stiffness)
  • Yellowing of the skin or eyes (jaundice)
  • Unusual bleeding or bruising
  • Sore throat, fever, or chills (signs of infection)
  • Seizures
  • Severe dizziness or fainting
  • Difficulty urinating
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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. Be sure to describe the symptoms you experienced.
If you have respiratory conditions, including asthma, chronic obstructive pulmonary disease (COPD), sleep apnea, or other breathing problems.
If you have liver problems or a history of Reye's syndrome.

This list is not exhaustive, and it is crucial to discuss all your health conditions and medications with your doctor.

To ensure safe treatment, provide your doctor and pharmacist with a comprehensive list of:
All prescription and over-the-counter (OTC) medications you are taking
Natural products and vitamins you are using
Any health problems you have

Do not start, stop, or adjust the dosage of any medication without first consulting your doctor to confirm it is safe to do so in conjunction with this medication.
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Precautions & Cautions

It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication.

Before operating a vehicle or engaging in any activity that requires alertness and clear vision, wait until you understand how this medication affects you.

This drug may interfere with the accuracy of certain pregnancy tests. If you are concerned about this, discuss it with your doctor.

If you have diabetes, it is crucial to closely monitor your blood sugar levels while taking this medication.

Prior to consuming alcohol, using marijuana or other cannabis products, or taking prescription or over-the-counter medications that may cause drowsiness, consult with your doctor.

You may be more susceptible to sunburn while taking this medication. To minimize this risk, avoid exposure to direct sunlight, sunlamps, and tanning beds. Use protective measures such as sunscreen, clothing, and eyewear that provide adequate sun protection.

This medication may increase the risk of seizures, particularly in individuals with a history of seizure disorders. Consult your doctor to determine if you are at a higher risk of experiencing seizures while taking this medication.

If you are 65 years or older, exercise caution when taking this medication, as you may be more prone to experiencing side effects.

If you are pregnant, planning to become pregnant, or breastfeeding, inform your doctor. It is necessary to discuss the potential benefits and risks of this medication to both you and your baby.
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Overdose Information

Overdose Symptoms:

  • Severe drowsiness or coma
  • Respiratory depression (slow, shallow breathing)
  • Hypotension (low blood pressure)
  • Tachycardia (fast heart rate)
  • Anticholinergic effects (dilated pupils, dry mouth, flushed skin, fever, urinary retention, paralytic ileus)
  • Extrapyramidal symptoms (involuntary movements)
  • Seizures
  • Cardiovascular collapse

What to Do:

Seek immediate medical attention. Call 911 or Poison Control at 1-800-222-1222. Treatment is supportive and symptomatic, including maintaining airway, breathing, and circulation. Naloxone may be considered if opioid co-ingestion is suspected. Physostigmine may be used for severe anticholinergic symptoms but is rarely recommended due to potential for adverse effects.

Drug Interactions

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Contraindicated Interactions

  • MAO inhibitors (concurrent use or within 14 days of MAOI discontinuation) - risk of severe extrapyramidal symptoms, hypotension, and CNS depression.
  • Other CNS depressants (e.g., opioids, benzodiazepines, barbiturates, alcohol) in children < 2 years due to increased risk of respiratory depression.
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Major Interactions

  • CNS depressants (e.g., opioids, benzodiazepines, barbiturates, alcohol, tricyclic antidepressants, other antihistamines) - additive CNS depression, respiratory depression, profound sedation.
  • Anticholinergic drugs (e.g., atropine, scopolamine, tricyclic antidepressants) - additive anticholinergic effects (dry mouth, blurred vision, urinary retention, constipation, paralytic ileus).
  • QT-prolonging drugs (e.g., antiarrhythmics, certain antipsychotics, macrolide antibiotics) - theoretical risk of QT prolongation and torsades de pointes (though promethazine's direct effect on QT is minor, caution is advised).
  • Dopamine agonists (e.g., bromocriptine, cabergoline) - promethazine's antidopaminergic effects may antagonize their therapeutic effects.
  • Epinephrine - promethazine's alpha-adrenergic blocking effects may reverse the pressor effect of epinephrine, leading to further blood pressure decrease.
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Moderate Interactions

  • Antihypertensives - additive hypotensive effects.
  • Cholinergic inhibitors (e.g., donepezil, rivastigmine) - promethazine's anticholinergic effects may reduce the efficacy of these drugs.
  • CYP2D6 inhibitors (e.g., fluoxetine, paroxetine, quinidine) - may increase promethazine plasma concentrations, leading to increased sedation and adverse effects.
  • Phenytoin - promethazine may increase phenytoin levels.
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Minor Interactions

  • Not readily available

Monitoring

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Baseline Monitoring

Patient history (especially respiratory, cardiac, neurological conditions)

Rationale: To identify contraindications or risk factors for adverse effects (e.g., respiratory depression, seizures, cardiovascular issues).

Timing: Prior to initiation of therapy.

Medication reconciliation

Rationale: To identify potential drug-drug interactions, especially with CNS depressants or anticholinergic agents.

Timing: Prior to initiation of therapy.

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Routine Monitoring

Level of consciousness/Sedation

Frequency: Regularly, especially during initial therapy or dose adjustments.

Target: Appropriate for therapeutic goal (e.g., mild sedation for sleep, alert for allergy).

Action Threshold: Excessive drowsiness, somnolence, or unresponsiveness; consider dose reduction or discontinuation.

Respiratory rate and effort

Frequency: Regularly, especially in pediatric patients or those with respiratory compromise.

Target: Normal for age.

Action Threshold: Bradypnea, shallow breathing, or signs of respiratory distress; discontinue and provide respiratory support.

Signs of anticholinergic effects (e.g., dry mouth, blurred vision, urinary retention, constipation)

Frequency: Daily, or as symptoms arise.

Target: Absence or mild, tolerable symptoms.

Action Threshold: Severe or intolerable symptoms; consider dose reduction or alternative therapy.

Signs of extrapyramidal symptoms (EPS) or neuroleptic malignant syndrome (NMS)

Frequency: Periodically, especially with higher doses or prolonged use.

Target: Absence of symptoms.

Action Threshold: Tremor, dystonia, akathisia, rigidity, fever, altered mental status; discontinue immediately and manage symptomatically.

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Symptom Monitoring

  • Excessive drowsiness or sedation
  • Difficulty breathing or shallow breathing
  • Dizziness or lightheadedness
  • Blurred vision
  • Dry mouth
  • Difficulty urinating
  • Constipation
  • Involuntary muscle movements (tremors, twitching)
  • Restlessness or agitation
  • Confusion or disorientation
  • Yellowing of skin or eyes (jaundice)
  • Unusual bleeding or bruising
  • Sore throat or fever (signs of blood dyscrasias)

Special Patient Groups

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Pregnancy

Category C. Use only if the potential benefit justifies the potential risk to the fetus. Promethazine has been used in pregnancy for nausea and vomiting, but data are limited. Avoid use in late third trimester due to potential for platelet aggregation inhibition in the neonate and increased risk of respiratory depression.

Trimester-Specific Risks:

First Trimester: Limited human data; animal studies show some adverse effects at high doses. Generally avoided unless clearly needed.
Second Trimester: More commonly used for hyperemesis gravidarum if other options fail, but still with caution.
Third Trimester: Avoid, especially within 2 weeks of delivery, due to potential for neonatal respiratory depression, extrapyramidal symptoms, and platelet aggregation inhibition.
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Lactation

L3 (Moderate Risk). Promethazine is excreted into breast milk. Due to the potential for sedation, respiratory depression, and anticholinergic effects in the infant, use with caution. Monitor infant for drowsiness, poor feeding, and breathing difficulties. Consider alternative agents, especially in preterm or jaundiced infants.

Infant Risk: Sedation, irritability, poor feeding, respiratory depression (especially in neonates/preterm infants), anticholinergic effects.
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Pediatric Use

Contraindicated in children younger than 2 years of age due to the risk of fatal respiratory depression. Use with extreme caution in children 2 years of age and older, and only when clearly indicated. Avoid concomitant use with other respiratory depressants. May cause paradoxical excitation in some children.

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Geriatric Use

Increased susceptibility to anticholinergic effects (e.g., dry mouth, blurred vision, urinary retention, constipation), sedation, dizziness, and hypotension. Start with lower doses and titrate slowly. Increased risk of falls. Avoid in elderly patients with dementia-related psychosis due to increased mortality risk (off-label use). Consider Beers Criteria recommendations.

Clinical Information

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Clinical Pearls

  • Promethazine is a potent sedative; warn patients about impaired driving and operating machinery.
  • Due to the black box warning, never administer to children under 2 years of age.
  • Oral route is preferred. If IV administration is absolutely necessary, dilute extensively and administer slowly into a large, patent vein to minimize risk of severe tissue injury (gangrene). Subcutaneous injection is contraindicated.
  • Can cause paradoxical excitation (restlessness, agitation) in some children and occasionally adults.
  • Has significant anticholinergic side effects; caution in patients with glaucoma, prostatic hypertrophy, or urinary retention.
  • May interfere with pregnancy tests (false positive or negative) and glucose tolerance tests.
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Alternative Therapies

  • For allergy: Diphenhydramine, Loratadine, Cetirizine, Fexofenadine
  • For nausea/vomiting: Ondansetron, Metoclopramide, Prochlorperazine
  • For sedation/insomnia: Diphenhydramine, Zolpidem, Trazodone
  • For motion sickness: Scopolamine (patch), Dimenhydrinate
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Cost & Coverage

Average Cost: $10 - $30 per 30 tablets (25mg)
Generic Available: Yes
Insurance Coverage: Tier 1 (Generic)
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General Drug Facts

If your symptoms or health issues persist or worsen, it is 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 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 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 details about the medication taken, the amount, and the time it happened.