Usage
- Proparacaine hydrochloride is prescribed for short-term local anesthesia of the cornea and conjunctiva. It is used for diagnostic procedures such as tonometry, gonioscopy, and corneal scraping, and for minor surgical procedures like removing foreign bodies or sutures. It’s also used before cataract surgery.
- Pharmacological Classification: Local anesthetic (ester type).
- Mechanism of Action: Proparacaine blocks the initiation and conduction of nerve impulses by decreasing the permeability of neuronal cell membranes to sodium ions. This action inhibits depolarization, preventing the transmission of pain signals.
Alternate Names
- Proparacaine Hydrochloride
- Brand Names: Alcaine, Ophthaine, Ocu-Caine, Ophthalmicaine, Ophthetic, Parcaine.
How It Works
- Pharmacodynamics: Proparacaine reversibly binds to sodium channels on sensory nerve endings in the cornea and conjunctiva, inhibiting nerve conduction and producing local anesthesia. Onset of action is rapid, within 30 seconds, and anesthesia lasts for approximately 10-20 minutes.
- Pharmacokinetics: Applied topically to the eye. Systemic absorption is minimal, hence systemic effects are rare. Metabolized by plasma cholinesterases and eliminated primarily via renal excretion.
- Mode of Action: Binds to and blocks voltage-gated sodium channels, inhibiting depolarization and subsequent nerve impulse propagation. This action prevents transmission of pain signals from the ocular surface.
- Receptor binding, enzyme inhibition, or neurotransmitter modulation: Primarily sodium channel blockade.
- Elimination Pathways: Primarily renal excretion of metabolites after hydrolysis by plasma cholinesterases.
Dosage
Standard Dosage
Adults:
- 1-2 drops instilled in the affected eye(s). For minor procedures, a single instillation may suffice. For longer procedures or deeper anesthesia (e.g., cataract surgery), instill 1 drop every 5-10 minutes for 5-7 doses.
Children:
- Similar dosing to adults. Safety and efficacy have not been specifically established in pediatric clinical trials, but the drug is generally well-tolerated in children under appropriate supervision.
Special Cases:
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Elderly Patients: No specific dose adjustments necessary based on age alone, but caution is advised in patients with underlying cardiac disease or hyperthyroidism.
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Patients with Renal Impairment: No formal studies available, but dose adjustments are generally not required due to minimal systemic absorption.
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Patients with Hepatic Dysfunction: No formal studies available, but dose adjustments are generally not required due to minimal systemic absorption.
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Patients with Comorbid Conditions: Use with caution in patients with allergies, cardiac disease, or hyperthyroidism.
Clinical Use Cases
- Intubation (Ophthalmic): Not applicable. Proparacaine is for topical ophthalmic use only.
- Surgical Procedures (Ophthalmic): 1 drop every 5–10 minutes for 5–7 doses for deeper anesthesia.
- Mechanical Ventilation: Not applicable.
- Intensive Care Unit (ICU) Use: Not applicable.
- Emergency Situations: Use for removal of foreign bodies.
Dosage Adjustments:
- Dose modifications are generally not needed for renal/hepatic impairment due to low systemic absorption.
Side Effects
Common Side Effects
- Transient burning, stinging, or discomfort upon instillation
- Conjunctival redness
- Tearing
- Increased blinking
Rare but Serious Side Effects
- Allergic reactions (e.g., contact dermatitis, hypersensitivity)
- Corneal epithelial defects (with prolonged or improper use)
Long-Term Effects
- Corneal opacification (rare, but possible with chronic misuse)
Adverse Drug Reactions (ADR)
- Severe allergic reactions (rare)
Contraindications
- Known hypersensitivity to proparacaine or any component of the formulation.
Drug Interactions
- No significant drug interactions are typically expected due to minimal systemic absorption. However, additive effects are possible with other local anesthetics. Theoretically, may interact with other ester-type local anesthetics, though this is not typically clinically significant with topical ophthalmic use.
Pregnancy and Breastfeeding
- Pregnancy Safety Category: C (Animal reproduction studies have not been conducted. It is not known whether this drug can cause fetal harm when administered to a pregnant woman). Use only if clearly needed.
- Breastfeeding: It is not known whether this drug is excreted in human milk. Caution is advised when administering to nursing mothers.
Drug Profile Summary
- Mechanism of Action: Sodium channel blocker, inhibiting nerve impulse transmission in the cornea and conjunctiva.
- Side Effects: Transient burning or stinging, redness, tearing. Rarely: allergic reactions, corneal epithelial defects.
- Contraindications: Hypersensitivity to proparacaine.
- Drug Interactions: No clinically significant interactions expected with topical use.
- Pregnancy & Breastfeeding: Use with caution; limited data available.
- Dosage: 1-2 drops topically in the affected eye(s). Repeat as needed for prolonged procedures.
- Monitoring Parameters: Monitor for signs of allergic reactions or corneal complications.
Popular Combinations
- No specific popular drug combinations are routinely used with proparacaine.
Precautions
- General Precautions: Use cautiously in patients with known allergies, cardiac disease, or hyperthyroidism. Avoid touching the tip of the dropper to the eye or any surface.
- Specific Populations:
- Pregnant Women: Use only if clearly needed.
- Breastfeeding Mothers: Exercise caution.
- Children & Elderly: Generally well-tolerated, but monitor for adverse reactions.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Proparacaine?
A: For most ophthalmic procedures, 1-2 drops are instilled in the affected eye(s). For procedures requiring deeper or longer-lasting anesthesia, instill 1 drop every 5-10 minutes for 5-7 doses.
Q2: How long does it take for Proparacaine to work?
A: Onset of anesthesia is usually within 30 seconds.
Q3: How long does the anesthetic effect of Proparacaine last?
A: Anesthesia typically lasts 10-20 minutes.
Q4: Can Proparacaine be used in children?
A: Yes, similar dosing guidelines apply to children, but use under the supervision of a healthcare professional.
Q5: What are the most common side effects of Proparacaine?
A: Burning or stinging upon instillation, redness, tearing, and increased blinking.
Q6: Are there any serious side effects of Proparacaine?
A: Rarely, allergic reactions or corneal epithelial defects can occur. Corneal opacification can occur with chronic misuse.
Q7: Can Proparacaine be used during pregnancy or breastfeeding?
A: Use with caution during pregnancy and breastfeeding. Consult with a doctor.
Q8: What are the contraindications for Proparacaine?
A: Known hypersensitivity to proparacaine or any component of the formulation.
Q9: How should Proparacaine be stored?
A: Store refrigerated at 2° to 8°C (36° to 46°F). Protect from light.
Q10: Does Proparacaine interact with other medications?
A: No significant drug interactions are usually expected with topical use.
