Usage
Alcaftadine is prescribed for the prevention of itching associated with allergic conjunctivitis. It is a topical ophthalmic antihistamine. Alcaftadine works by blocking histamine H1 receptors and stabilizing mast cells in the conjunctiva, thus reducing the allergic response and relieving itching.
Alternate Names
Lastacaft (brand name)
How It Works
Pharmacodynamics: Alcaftadine is a selective H1 receptor antagonist and also exhibits some H2 and H4 receptor antagonism. It effectively reduces itching by blocking the action of histamine at its receptors in the eye. It also stabilizes mast cells, which are key players in the allergic response, preventing the release of inflammatory mediators.
Pharmacokinetics: Alcaftadine ophthalmic solution is administered topically to the eye. Systemic absorption is minimal, resulting in low plasma concentrations. It is metabolized to its carboxylic acid form. The elimination pathway is not fully characterized, but it is likely that a significant portion of the drug is eliminated unchanged in the urine due to limited systemic exposure.
Mode of Action: Alcaftadine binds to and blocks H1 histamine receptors in the conjunctiva of the eye. This prevents histamine, released during an allergic reaction, from binding to these receptors and triggering the downstream effects that lead to itching, redness, and other allergic symptoms. The drug also inhibits the release of histamine from mast cells and prevents allergen-induced disruption of tight junction proteins in the conjunctival epithelium, which can contribute to the allergic response.
Dosage
Standard Dosage
Adults: One drop in each affected eye once daily.
Children:
- 2 years and older: One drop in each affected eye once daily.
- Younger than 2 years: Safety and efficacy have not been established.
Special Cases:
- Elderly Patients: No dosage adjustment is generally necessary.
- Patients with Renal Impairment: No dosage adjustment is necessary due to minimal systemic absorption.
- Patients with Hepatic Dysfunction: No dosage adjustment is necessary due to minimal systemic absorption.
- Patients with Comorbid Conditions: Exercise caution in patients with glaucoma or other eye conditions. Monitor intraocular pressure.
Clinical Use Cases
Alcaftadine is primarily indicated for allergic conjunctivitis. There are no specific dosage recommendations for intubation, surgical procedures, mechanical ventilation, ICU use, or emergency situations.
Dosage Adjustments
No specific dosage adjustments are required based on renal or hepatic impairment.
Side Effects
Common Side Effects
- Eye irritation (burning/stinging)
- Headache
- Nasopharyngitis (cold symptoms)
- Eye redness
- Eye pruritus (itching)
Rare but Serious Side Effects
- Allergic reactions (e.g., swelling of face, lips, tongue, or throat; difficulty breathing; hives)
Long-Term Effects
No specific long-term side effects have been reported.
Adverse Drug Reactions (ADR)
Serious allergic reactions (as above) require immediate medical attention.
Contraindications
- Hypersensitivity to alcaftadine or any component of the formulation.
Drug Interactions
- No clinically significant drug interactions have been definitively established for topical alcaftadine due to its minimal systemic absorption. However, caution should be exercised when using multiple topical ophthalmic medications concurrently. Administer at least 5 minutes apart.
- Potential interactions with oral antihistamines or antidepressants are unlikely due to minimal systemic absorption, however concurrent use should be discussed with the physician.
Pregnancy and Breastfeeding
- Pregnancy: Pregnancy Category C. Use only if the potential benefit justifies the potential risk to the fetus.
- Breastfeeding: It is not known whether alcaftadine is excreted in human milk. Exercise caution when administering to nursing women.
Drug Profile Summary
- Mechanism of Action: H1 receptor antagonist, mast cell stabilizer.
- Side Effects: Eye irritation, headache, nasopharyngitis, eye redness, eye pruritus.
- Contraindications: Hypersensitivity.
- Drug Interactions: Minimal due to low systemic absorption; administer other eye medications 5 minutes apart.
- Pregnancy & Breastfeeding: Use with caution; potential fetal risk.
- Dosage: One drop in each affected eye once daily.
- Monitoring Parameters: Monitor intraocular pressure, especially in patients with glaucoma.
Popular Combinations
Alcaftadine is typically used as monotherapy.
Precautions
- General Precautions: Avoid touching the dropper tip to any surface to prevent contamination.
- Specific Populations: As detailed above in “Pregnancy and Breastfeeding”, “Children” section under “Dosage.”
- Lifestyle Considerations: If blurred vision occurs, avoid driving or operating machinery.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Alcaftadine?
A: One drop in each affected eye once daily for adults and children 2 years and older.
Q2: How does Alcaftadine work?
A: It blocks H1 histamine receptors, stabilizes mast cells, and inhibits histamine release, reducing allergic symptoms.
Q3: What are the common side effects?
A: Eye irritation, burning/stinging, headache, nasopharyngitis.
A: Remove contact lenses before instillation. Reinsert lenses 10 minutes after administration.
Q5: Is Alcaftadine safe during pregnancy?
A: Pregnancy Category C. Use only if the benefit outweighs the risk. Consult your doctor.
Q6: Can I use Alcaftadine while breastfeeding?
A: It is unknown if it passes into breast milk. Consult your doctor.
Q7: How long does Alcaftadine take to work?
A: It typically provides relief within minutes.
Q8: What should I do if I miss a dose?
A: Instill the missed dose as soon as possible. If it is almost time for the next dose, skip the missed dose and return to your regular schedule.
Q9: Can Alcaftadine be used for other types of eye irritation?
A: No. It is specifically indicated for allergic conjunctivitis. Do not use it for contact lens-related irritation or other eye conditions without consulting a physician.
Q10: What should I tell my patients about proper administration?
A: Tilt head back, pull down lower eyelid, instill one drop, and close eyes gently for 1-2 minutes. Avoid touching the dropper tip to the eye or any other surface.
