Usage
- This combination medication is primarily prescribed for the relief of cough and upper respiratory symptoms, including nasal congestion, associated with allergies or the common cold.
- Pharmacological Classifications: Antihistamine (Bilastine), Antitussive (Dextromethorphan Hydrochloride), Nasal Decongestant (Phenylephrine Hydrochloride).
- Mechanism of Action: Bilastine acts as a peripheral H1-receptor antagonist, reducing the effects of histamine, a chemical mediator responsible for allergic symptoms. Dextromethorphan hydrochloride suppresses the cough reflex by acting centrally on the cough center in the brain. Phenylephrine hydrochloride acts as a nasal decongestant by constricting blood vessels in the nasal mucosa, reducing swelling and congestion.
Alternate Names
- Bilastine/Dextromethorphan/Phenylephrine combination.
- Brand Names: Alex-BL Syrup, Bisalatin Dexter Syrup, Costus BT Syrup. (Please note that brand names may vary regionally.)
How It Works
- Pharmacodynamics: Bilastine selectively blocks peripheral H1 receptors, mitigating the effects of histamine release (itching, sneezing, runny nose). Dextromethorphan suppresses the cough reflex centrally. Phenylephrine constricts blood vessels in the nasal mucosa, alleviating congestion.
- Pharmacokinetics:
- Bilastine: Well absorbed orally, minimally metabolized, primarily excreted renally. Food or fruit juice can decrease its absorption.
- Dextromethorphan: Extensively metabolized in the liver, primarily by CYP2D6. Genetic polymorphisms of CYP2D6 can influence its effectiveness and potential for adverse events.
- Phenylephrine: Metabolized by monoamine oxidase in the intestine and liver.
- Mode of Action: Bilastine competitively antagonizes histamine at H1 receptors. Dextromethorphan acts on sigma opioid receptors in the central nervous system to suppress cough. Phenylephrine acts on alpha-adrenergic receptors in the nasal mucosa.
- Elimination Pathways: Bilastine mainly renal excretion. Dextromethorphan primarily hepatic metabolism and renal excretion. Phenylephrine hepatic and intestinal metabolism.
Dosage
Standard Dosage
Adults:
- Typically, 10 mL (containing Bilastine 3.3 mg, Dextromethorphan Hydrobromide 10 mg, and Phenylephrine Hydrochloride 5 mg) every 4-6 hours as needed.
- Do not exceed 4 doses (40 mL) within a 24-hour period.
Children:
- 12 years and older: Same as adult dosage.
- 6 to under 12 years: 5 mL every 4-6 hours as needed, not exceeding 4 doses (20 mL) in 24 hours.
- Under 6 years: Consult a physician. This combination is generally not recommended for young children.
Special Cases:
- Elderly Patients: Start with a lower dose and monitor closely for side effects. Dosage adjustments may be necessary based on renal and hepatic function.
- Patients with Renal Impairment: Bilastine dosage adjustment is generally not necessary. However, caution is advised with Dextromethorphan, and adjustments might be needed depending on the severity of the impairment.
- Patients with Hepatic Dysfunction: Caution is recommended. Monitor for adverse effects. Dose adjustments, especially for dextromethorphan, might be necessary based on the degree of impairment.
- Patients with Comorbid Conditions: Use with caution in patients with hypertension, diabetes, heart disease, hyperthyroidism, glaucoma, or prostatic hypertrophy. Consult a physician for individualized dosing recommendations.
Clinical Use Cases
This particular combination (Bilastine/Dextromethorphan/Phenylephrine) is not typically indicated for use in clinical settings such as intubation, surgical procedures, mechanical ventilation, ICU use, or emergency situations.
Dosage Adjustments
Dose modifications should be considered based on individual patient factors, including renal/hepatic function, age, and presence of other medical conditions. Consult a doctor if you have any questions about dosage modifications.
Side Effects
Common Side Effects:
- Drowsiness
- Dizziness
- Headache
- Nausea
- Vomiting
- Dry mouth
- Nervousness/Restlessness
- Difficulty sleeping
Rare but Serious Side Effects:
- Allergic reactions (rash, itching, swelling, severe dizziness, difficulty breathing)
- Hallucinations
- Seizures
- Irregular heartbeat
- Severe drowsiness
Long-Term Effects:
- Prolonged use of dextromethorphan, especially at higher than recommended doses, can lead to dependence.
Contraindications
- Hypersensitivity to any component of the medication.
- Concurrent use of Monoamine Oxidase Inhibitors (MAOIs) or within 14 days of stopping MAOIs.
- Respiratory failure or severe lung disease.
- Concurrent use of other sympathomimetic decongestants.
- Closed-angle glaucoma.
- Severe hypertension or coronary artery disease.
Drug Interactions
- MAOIs: Concomitant use can be potentially fatal.
- Alcohol and CNS depressants: Increased drowsiness and dizziness.
- Other cough/cold medications containing decongestants or antihistamines: Avoid concurrent use due to increased risk of adverse effects.
- Serotonin reuptake inhibitors (SSRIs): Possible serotonin syndrome.
- CYP2D6 inhibitors or inducers: Can alter dextromethorphan metabolism.
- Medications metabolized by CYP2D6 (e.g., some antidepressants, beta-blockers): Potential for altered drug levels.
Pregnancy and Breastfeeding
- Pregnancy: Consult a physician before use. The safety of this combination in pregnancy has not been definitively established. Use only if the benefits outweigh the potential risks.
- Breastfeeding: Caution is advised. Consult a physician. The components of this combination may be excreted in breast milk and could potentially affect the infant.
Drug Profile Summary
- Mechanism of Action: Antihistamine, antitussive, and decongestant.
- Side Effects: Drowsiness, dizziness, headache, nausea, vomiting, dry mouth.
- Contraindications: Hypersensitivity, concurrent MAOI use, respiratory failure.
- Drug Interactions: MAOIs, alcohol, CNS depressants, SSRIs, CYP2D6 inhibitors/inducers.
- Pregnancy & Breastfeeding: Consult a physician before use.
- Dosage: See detailed dosage section above.
- Monitoring Parameters: Monitor blood pressure, respiratory rate, and any signs of adverse effects.
Popular Combinations
This combination itself is a commonly used formulation. Separate components may be combined with other medications as needed, but always under medical supervision.
Precautions
- Pre-existing medical conditions: Evaluate carefully, especially in patients with cardiac, respiratory, or metabolic issues.
- Pregnant Women: Assess potential risks and benefits.
- Breastfeeding Mothers: Assess potential infant exposure and risk.
- Children & Elderly: Age-specific dosage and careful monitoring.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Bilastine + Dextromethorphan Hydrochloride + Phenylephrine?
A: See the detailed dosage section above.
Q2: Can I take this combination if I am pregnant or breastfeeding?
A: Consult your physician before use during pregnancy or while breastfeeding.
Q3: What are the common side effects?
A: Common side effects include drowsiness, dizziness, headache, nausea, vomiting, and dry mouth.
Q4: Can I drink alcohol while taking this medicine?
A: No, avoid alcohol as it can exacerbate drowsiness and dizziness.
Q5: Are there any serious drug interactions I should be aware of?
A: Yes, avoid concomitant use with MAOIs, as this can be potentially fatal. Inform your doctor about all medications you are taking, including OTC drugs and supplements.
Q6: Can this medication be used for children?
A: It is generally not recommended for children under 6 years old. For older children, refer to the pediatric dosage guidelines.
Q7: What should I do if I experience severe side effects?
A: Discontinue the medication immediately and seek medical attention.
Q8: How long can I take this medication?
A: This combination is typically used for short-term relief of symptoms. Consult your doctor if symptoms persist for more than 7 days.
Q9: Should I avoid driving or operating machinery while taking this medication?
A: Use caution when driving or operating machinery as this combination can cause drowsiness or dizziness.
Q10: What should I do if I miss a dose?
A: If you miss a dose, take it as soon as you remember. However, if it is almost time for your next dose, skip the missed dose and continue your regular dosing schedule. Do not double the dose to catch up.
