The FDA prescribing information lists dosage forms including capsules (40 mg, 80 mg) and tablets (40 mg, 80 mg, 120 mg, 160 mg). Both dosage forms are bioequivalent and interchangeable.

1. Starting Dosage: Adults Based on Body Weight, Children Based on Body Surface Area

1) Adults and Pediatric Patients Aged 12 Years and Older (Based on Body Weight)

For patients weighing less than 50 kg, the recommended dosage is 120 mg orally twice daily; for patients weighing 50 kg or more, the recommended dosage is 160 mg orally twice daily.

2) Pediatric Patients Aged 2 to Less Than 12 Years (Based on Body Surface Area)

0.33 to 0.65 m²: 40 mg orally three times daily.

0.66 to 1.08 m²: 80 mg orally twice daily.

1.09 to 1.52 m²: 120 mg orally twice daily.

1.53 m² or greater: 160 mg orally twice daily.

Body surface area less than 0.33 m²: Not recommended.

Dosing for pediatric patients is based on body surface area because children have a wide range of weights and significant body shape differences, making body surface area a better reflector of drug distribution than weight alone.

2. General Principles for Dose Modifications

When adverse reactions occur, physicians will lower the dosage step by step according to the following pathways:

Current dose of 160 mg twice daily: First reduction to 120 mg twice daily; second reduction to 80 mg twice daily; third reduction to 40 mg twice daily.

Current dose of 120 mg twice daily: First reduction to 80 mg twice daily; second reduction to 40 mg twice daily; third reduction to 40 mg once daily.

Current dose of 80 mg twice daily: First reduction to 40 mg twice daily; second reduction to 40 mg once daily; third step is permanent discontinuation.

Current dose of 40 mg three times daily: First reduction to 40 mg twice daily; second reduction to 40 mg once daily; third step is permanent discontinuation.

3. Administration Guidelines

1. Swallow whole; do not crush or chew. This applies to both capsules and tablets.

2. May be taken with or without food. High-fat meals do not affect the absorption of this drug, so special dietary restrictions or fasting are not required.

3. If you are concurrently taking a proton pump inhibitor (PPI), this medication must be taken with food.

4. For patients who cannot swallow whole or who use a feeding tube, a specific dispersion administration procedure must be followed. FDA prescribing information restriction: Only the 40 mg tablets can be used to prepare a suspension; other strengths must not be used.

4. Administration for Patients with Swallowing Difficulties

1) Oral Administration

Place the required number of 40 mg tablets for the prescribed dose (1, 2, 3, or 4 tablets) into a glass or medicine cup. Add approximately 1 tablespoon (15 mL) of room-temperature or refrigerated water, or 100% pureed carrots.

Stir intermittently until the tablets disperse (about 7 to 10 minutes). Sediment or cloudiness may appear when using water, which is normal.

Administer the full mixture immediately. Add another tablespoon (15 mL) of water to the cup, swirl or stir to gather any remaining medication, and consume immediately.

Discard if not administered within 2 hours of preparation.

2) Administration via Feeding Tube (Gastric or Nasogastric Tube)

Use polyurethane tubes (French size 8 or larger), polyvinyl chloride tubes (French size 10 or larger), or silicone gastric tubes (French size 14 or larger).

Place the required number of 40 mg tablets into at least 10 mL of room-temperature water and stir intermittently for about 7 to 10 minutes until dispersed.

Flush the feeding tube according to the manufacturer instructions first. Draw the suspension into an enteral syringe and immediately administer through the tube. Add 5 mL of water, swirl to gather remaining medication, and administer through the tube in the same manner.

Repeat flushing as necessary to ensure complete dose delivery. Finally, flush the feeding tube again following manufacturer instructions. Discard if not administered within 2 hours of preparation.