Usage
Phenylephrine + Triprolidine is prescribed for the temporary relief of symptoms associated with the common cold, hay fever (allergic rhinitis), and other upper respiratory allergies. These symptoms include:
- Nasal congestion (stuffy nose)
- Runny nose
- Sneezing
- Itching of the nose or throat
- Itchy, watery eyes
Pharmacological Classification:
This combination medication includes two classes of drugs:
- Phenylephrine: Decongestant (alpha-adrenergic agonist)
- Triprolidine: Antihistamine (H1 receptor antagonist)
Mechanism of Action:
- Phenylephrine: Constricts blood vessels in the nasal passages, reducing swelling and congestion.
- Triprolidine: Blocks the action of histamine, a chemical mediator responsible for allergic symptoms.
Alternate Names
While the generic name is Phenylephrine + Triprolidine, it is marketed under various brand names like Prohist LQ. There may be other regional or international brand names.
How It Works
Pharmacodynamics:
- Phenylephrine: Stimulates alpha-adrenergic receptors in the nasal mucosa, causing vasoconstriction and reducing nasal congestion. It may also slightly increase blood pressure.
- Triprolidine: Competitively antagonizes H1 histamine receptors, relieving symptoms like sneezing, itching, and runny nose. It also has mild sedative properties.
Pharmacokinetics:
- Absorption: Both drugs are well-absorbed orally.
- Metabolism: Primarily hepatic metabolism for both drugs.
- Elimination: Excreted mainly through the kidneys.
Mode of Action: As described above, phenylephrine acts on alpha-adrenergic receptors causing vasoconstriction, while triprolidine acts on H1 histamine receptors blocking histamine’s effects.
Receptor Binding, Enzyme Inhibition or Neurotransmitter Modulation: Phenylephrine binds to alpha-adrenergic receptors, while triprolidine competitively binds to H1 histamine receptors. There is no significant enzyme inhibition or neurotransmitter modulation directly associated with these two drugs.
Elimination Pathways: Hepatic metabolism and renal excretion are the primary elimination pathways. Specific CYP enzyme involvement may vary.
Dosage
Standard Dosage
Adults:
Typically, 5 mL of oral liquid every 4-6 hours, not exceeding 4 doses in 24 hours. Dosages may vary based on the specific product.
Children:
- 2-6 years: Use with caution as advised by the physician. Dosages must be adjusted based on weight or age, and usually a lower volume is administered.
- 6-11 years: 2.5 mL orally every 6 hours, not exceeding 4 doses daily.
- 12 years and older: Adult dose (5 mL orally every 4-6 hours, not exceeding 4 doses in 24 hours).
Special Cases:
- Elderly Patients: Start with a lower dose due to potential increased sensitivity. Monitor for adverse effects like dizziness, drowsiness, confusion, constipation, rapid heartbeat, difficulty urinating, and blood pressure changes.
- Patients with Renal Impairment: Dose adjustment may be necessary depending on the degree of impairment.
- Patients with Hepatic Dysfunction: Dose adjustment may be necessary depending on the degree of impairment.
- Patients with Comorbid Conditions: Use with caution in patients with glaucoma, hypertension, diabetes, cardiovascular disease, hyperthyroidism, prostatic hypertrophy, asthma, or other respiratory diseases. Dosage adjustments may be needed.
Clinical Use Cases
The combination of phenylephrine and triprolidine is not typically used in clinical settings such as intubation, surgical procedures, mechanical ventilation, ICU, or emergency situations. Its primary use is for symptomatic relief of common cold and allergy symptoms.
Dosage Adjustments
Dose adjustments should be made based on individual patient characteristics, including renal or hepatic dysfunction, other medical conditions, and concomitant medications.
Side Effects
Common Side Effects
- Drowsiness
- Dizziness
- Dry mouth, nose, and throat
- Blurred vision
- Nausea, stomach upset
- Constipation
- Nervousness or excitability
- Difficulty sleeping
Rare but Serious Side Effects
- Allergic reactions (hives, difficulty breathing, swelling)
- Rapid or irregular heartbeat
- Seizures
- Hallucinations
- Difficulty urinating
- Severe skin reactions
Long-Term Effects
Long-term continuous use is generally not recommended due to potential tolerance and adverse effects.
Adverse Drug Reactions (ADR)
Any severe or persistent side effects should be considered as potential ADRs and necessitate immediate medical attention.
Contraindications
- Hypersensitivity to phenylephrine or triprolidine
- MAO inhibitor use within the past 14 days
- Severe cardiovascular disease
- Uncontrolled hypertension
- Narrow-angle glaucoma
- Severe coronary artery disease
- Prostatic hypertrophy with urinary retention
- Pyloric or duodenal obstruction
- Untreated hyperthyroidism
Drug Interactions
- MAO inhibitors
- Other antihistamines or decongestants
- Alcohol
- Sedatives, hypnotics, tranquilizers
- Tricyclic antidepressants
- Beta-blockers
- Digoxin
- Antihypertensives
Pregnancy and Breastfeeding
Pregnancy Safety Category: C. Use only if the potential benefit outweighs the risk to the fetus. Consult with a doctor.
Breastfeeding: It is not recommended for use during breastfeeding as it may pass into breast milk.
Drug Profile Summary
- Mechanism of Action: Phenylephrine: Alpha-adrenergic agonist, decongestant. Triprolidine: H1 receptor antagonist, antihistamine.
- Side Effects: Drowsiness, dizziness, dry mouth, blurred vision, nausea, constipation.
- Contraindications: Hypersensitivity, MAO inhibitor use, severe cardiovascular disease, uncontrolled hypertension, narrow-angle glaucoma.
- Drug Interactions: MAOIs, other antihistamines/decongestants, alcohol, sedatives.
- Pregnancy & Breastfeeding: Use with caution during pregnancy. Avoid during breastfeeding.
- Dosage: Adults: 5 mL every 4-6 hours. Children: Dose adjusted by age and weight.
- Monitoring Parameters: Blood pressure, heart rate, respiratory rate, mental status.
Popular Combinations
Phenylephrine and triprolidine are often combined with other medications like acetaminophen, dextromethorphan, or codeine for broader symptomatic relief. However, combining these medications without a doctor’s advice is risky.
Precautions
- Pre-existing medical conditions should be carefully evaluated.
- Use cautiously in elderly patients and those with renal or hepatic impairment.
- Avoid alcohol and other CNS depressants.
- May impair alertness and coordination.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Phenylephrine + Triprolidine?
A: Adults: 5 mL every 4-6 hours, not exceeding 4 doses daily. Children: dosage adjusted by age and weight, consult a healthcare professional.
Q2: What are the common side effects?
A: Drowsiness, dizziness, dry mouth, blurred vision, and gastrointestinal upset are common.
Q3: Can I take this medicine if I am pregnant or breastfeeding?
A: Consult with your doctor. Use during pregnancy only if clearly needed. It’s generally advised to avoid it while breastfeeding.
Q4: What other medications should I avoid while taking Phenylephrine + Triprolidine?
A: Avoid MAO inhibitors, other antihistamines/decongestants, alcohol, and sedatives. Consult your doctor about other medications.
Q5: What conditions could be worsened by this medication?
A: Pre-existing conditions such as glaucoma, hypertension, cardiovascular disease, hyperthyroidism, prostatic hypertrophy, asthma, or other respiratory diseases could be exacerbated.
Q6: How long can I take this medication?
A: It is recommended for short-term use only, typically until your symptoms subside. Consult with your doctor for usage exceeding 7 days.
Q7: Can I drive or operate machinery while taking this medication?
A: This medicine can cause drowsiness or dizziness. Avoid these activities until you know how it affects you.
Q8: What should I do if I experience severe or unusual side effects?
A: Discontinue use immediately and seek medical attention.
Q9: Is this medication addictive?
A: Phenylephrine and triprolidine are not considered addictive. However, some formulations may include other ingredients with addictive potential, such as codeine.
Q10: Are there any dietary restrictions while using this medicine?
A: While there are no strict dietary restrictions, avoiding alcohol is crucial. Consult your doctor or pharmacist for advice on other potential interactions.
