Daybue Stix

Dosage and Administration ( 2.1 , 2.2 , 2.3 , 2.6 ) 12/2025

1 INDICATIONS AND USAGE DAYBUE and DAYBUE STIX are indicated for the treatment of Rett syndrome in adults and pediatric patients 2 years of age and older. DAYBUE and DAYBUE STIX are indicated for the treatment of Rett syndrome in adults and pediatric patients 2 years of age and older. ( 1 )

2 DOSAGE AND ADMINISTRATION Recommended dosage is twice daily, morning and evening, according to patient weight. DAYBUE or DAYBUE STIX can be given with or without food. ( 2.1 ) Patient Weight Recommended Dosage 9 kg to less than 12 kg 5,000 mg twice daily 12 kg to less than 20 kg 6,000 mg twice daily 20 kg to less than 35 kg 8,000 mg twice daily 35 kg to less than 50 kg 10,000 mg twice daily 50 kg or more 12,000 mg twice daily Can be given orally or via gastrostomy (G) tube; doses administered via gastrojejunal (GJ) tubes must be administered through the G-port. ( 2.1 ) See Full Prescribing Information for instruction on dissolving DAYBUE STIX for oral solution powder. ( 2.3 ) See Full Prescribing Information for dosage recommendations in patients with renal impairment. ( 2.6 , 8.6 ) 2.1 Recommended Dosage The recommended dosage of DAYBUE or DAYBUE STIX is based on patient weight as shown in Table 1 . Administer DAYBUE or DAYBUE STIX orally or via gastrostomy (G) tube twice daily, in the morning and evening, with or without food. Doses administered via gastrojejunal (GJ) tubes must be administered through the G-port. Table 1 Recommended Dosage of DAYBUE or DAYBUE STIX in Patients 2 Years of Age and Older Patient Weight Recommended Dosage 9 kg to less than 12 kg 5,000 mg twice daily 12 kg to less than 20 kg 6,000 mg twice daily 20 kg to less than 35 kg 8,000 mg twice daily 35 kg to less than 50 kg 10,000 mg twice daily 50 kg or more 12,000 mg twice daily 2.2 DAYBUE Oral Solution Preparation Table 2 includes the volume of DAYBUE oral solution to administer for the corresponding recommended dosage [see Dosage and Administration (2.1 , 2.6) ] . A calibrated measuring device, such as an oral syringe or oral dosing cup, should be obtained from the pharmacy to measure and deliver the prescribed dose accurately. A household measuring cup, teaspoon, or tablespoon is not an adequate measuring device. Table 2 Recommended Volume of DAYBUE Oral Solution for Administration Dosage DAYBUE Oral Solution Volume 2,500 mg twice daily Dosage for patients with moderate renal impairment [see Dosage and Administration (2.6) ] 12.5 mL twice daily 3,000 mg twice daily 15 mL twice daily 4,000 mg twice daily 20 mL twice daily 5,000 mg twice daily 25 mL twice daily 6,000 mg twice daily 30 mL twice daily 8,000 mg twice daily 40 mL twice daily 10,000 mg twice daily 50 mL twice daily 12,000 mg twice daily 60 mL twice daily Discard any unused DAYBUE oral solution after 14 days of first opening the bottle [see How Supplied/Storage and Handling (16.2) ] . 2.3 DAYBUE STIX for Oral Solution Preparation Prior to administration, DAYBUE STIX for oral solution powder must be dissolved in a cold to room temperature water or water-based beverage (juice, tea, lemonade, limeade, or liquid hydration). Preparation of DAYBUE STIX Determine the correct dosage as shown in Table 1 or Table 4 (for patients with moderate renal impairment). Select the appropriate packet strength and number of packets required for each dose, as shown in Table 3 . Determine the appropriate volume of liquid within the recommended volume range as shown in Table 3 , based on individual patient factors (e.g., age, palatability). Measure the volume of liquid determined in Step 3 by using a calibrated measuring device obtained from the pharmacy. Empty the entire contents of the DAYBUE STIX packet(s) into the measured liquid. Do not attempt to use partial packets to prepare a dose. Stir until the powder is completely dissolved. Administer the prepared oral solution immediately; do not store for future use. Discard any prepared oral solution that is not immediately administered. Table 3 Preparation Instructions for DAYBUE STIX for Oral Solution Powder Dose DAYBUE STIX Packet(s) Needed to Prepare Each Dose Volume of Liquid Required to Dissolve Entire Dose Liquid types include water or water-based beverage. , Volume should be selected within the recommended range based on individual patient factors. 5,000 m …

3 DOSAGE FORMS AND STRENGTHS Oral solution: 200 mg/mL of a pink to red, strawberry flavored solution. For oral solution: 5,000 mg, 6,000 mg, or 8,000 mg of white, off-white to pinkish powder with strawberry flavor, packaged in individual packets. Oral solution: 200 mg/mL ( 3 ) For oral solution: 5,000 mg, 6,000 mg, or 8,000 mg per packet ( 3 )

4 CONTRAINDICATIONS None. None. ( 4 )

6 ADVERSE REACTIONS The following clinically significant adverse reactions are described elsewhere in labeling: Diarrhea [see Warnings and Precautions (5.1) ] Weight Loss [see Warnings and Precautions (5.2) ] Vomiting [see Warnings and Precautions (5.3) ] The most common adverse reactions (that occurred in at least 10% of DAYBUE-treated patients and at least 2% greater than in placebo) were diarrhea and vomiting. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Acadia Pharmaceuticals Inc. at 1-844-422-2342 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. In controlled and uncontrolled trials in patients with Rett syndrome, 260 patients ages 2 to 40 years were treated with DAYBUE, including 112 patients treated for more than 6 months, 92 patients treated for more than 1 year, and 44 patients treated for more than 2 years. The safety of DAYBUE STIX has been established from an adequate, well-controlled study, and open-label studies of DAYBUE [see Clinical Studies (14) ] . Below is a display of the adverse reactions of DAYBUE in these studies. Adult and Pediatric Patients with Rett Syndrome 5 Years of Age and Older The safety of DAYBUE was evaluated in a randomized, double-blind, placebo-controlled, 12-week study of patients with Rett syndrome (Study 1) [see Clinical Studies (14) ] . In Study 1, 93 patients received DAYBUE and 94 patients received placebo. All patients were female, 92% were White, and the mean age was 11 years (range 5 to 20 years). Adverse Reactions Leading to Discontinuation of Treatment Eighteen patients (19%) receiving DAYBUE had adverse reactions that led to withdrawal from the study. The most common adverse reaction leading to discontinuation of treatment with DAYBUE was diarrhea (15%). Common Adverse Reactions Adverse reactions that occurred in Study 1 in at least 5% of patients treated with DAYBUE and were at least 2% more frequent than in patients on placebo are presented in Table 5 . Table 5 Adverse Reactions in at Least 5% of Patients Treated with DAYBUE and at Least 2% Greater than Placebo in Study 1 Adverse Reaction DAYBUE (N=93) % Placebo (N=94) % Diarrhea 82 20 Vomiting 29 12 Fever 9 4 Seizure 9 6 Anxiety 8 1 Decreased appetite 8 2 Fatigue 8 2 Nasopharyngitis 5 1 Pediatric Patients with Rett Syndrome 2 to 4 Years of Age In an open-label study in pediatric patients 2 to 4 years of age with Rett syndrome (N=15), a total of 13 patients received DAYBUE for at least 12 weeks and 10 patients received DAYBUE for at least 12 months. Adverse reactions in pediatric patients 2 to 4 years of age treated with DAYBUE were similar to those reported in adult and pediatric patients 5 years of age and older with Rett syndrome in Study 1. 6.2 Postmarketing Experience The following adverse reactions have been identified during postapproval use of DAYBUE. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Aspiration and aspiration pneumonia secondary to vomiting [see Warnings and Precautions (5.3) ] .

7 DRUG INTERACTIONS Orally administered CYP3A and/or P-gp sensitive substrates for which a small change in substrate plasma concentration may lead to serious adverse reactions: closely monitor for adverse reactions with concomitant use. ( 7.1 ) 7.1 Effect of DAYBUE and DAYBUE STIX on Other Drugs CYP3A and/or P-gp Substrates Closely monitor patients when DAYBUE or DAYBUE STIX is administered concomitantly with sensitive CYP3A and/or P-gp substrates where minimal increases in the plasma concentration of these substrates may lead to serious adverse reactions. Trofinetide, a weak inhibitor of CYP3A and an inhibitor of P-gp, increased the plasma concentrations of CYP3A and/or P-gp substrates [see Clinical Pharmacology (12.3) ] , which may increase the risk of adverse reactions associated with these substrates.

8 USE IN SPECIFIC POPULATIONS Severe renal impairment: DAYBUE and DAYBUE STIX are not recommended. ( 8.6 ) 8.1 Pregnancy Risk Summary There are no adequate data on the developmental risks associated with the use of DAYBUE or DAYBUE STIX in pregnant women. No adverse developmental effects were observed following oral administration of trofinetide to pregnant animals at doses associated with plasma exposures below those used clinically [see Animal Data ] . The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively. Data Animal Data Oral administration of trofinetide (0, 150, 450, or 1000 mg/kg twice daily; 0, 300, 900, or 2000 mg/kg/day) to pregnant rats during the period of organogenesis resulted in no adverse effects on embryofetal development. At the highest dose tested, plasma exposure (AUC) was less than that in humans at the maximum recommended human dose (MRHD) of 12,000 mg twice daily (24,000 mg/day). Oral administration of trofinetide (0, 75, 150, or 300 mg/kg twice daily; 0, 150, 300, or 600 mg/kg/day) to pregnant rabbits during the period of organogenesis resulted in no adverse effects on embryofetal development. At the highest dose tested, plasma exposure (AUC) was less than that in humans at the MRHD. Oral administration of trofinetide (0, 150, 450, or 1000 mg/kg twice daily; 0, 300, 900, or 2000 mg/kg/day) to rats throughout pregnancy and lactation resulted in no adverse effects on pre- and postnatal development. At the highest dose tested, plasma exposure (AUC) was less than that in humans at the MRHD. 8.2 Lactation Risk Summary There is no information regarding the presence of trofinetide or its metabolites in human milk, the effects on the breastfed infant, or the effects on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for DAYBUE or DAYBUE STIX and any potential adverse effects on the breastfed infant from the treatment or from the underlying maternal condition. 8.4 Pediatric Use The safety and effectiveness of DAYBUE and DAYBUE STIX for the treatment of Rett syndrome have been established in pediatric patients aged 2 years and older. The safety and effectiveness of DAYBUE for the treatment of Rett syndrome in pediatric patients 5 years of age and older was established in a randomized, double-blind, placebo-controlled, 12-week study (Study 1), which included 108 pediatric patients age 5 to less than 12 years of age and 47 pediatric patients age 12 to less than 17 years of age [see Adverse Reactions (6.1) and Clinical Studies (14) ]. Use of DAYBUE or DAYBUE STIX in patients 2 to 4 years of age is supported by evidence from Study 1 and pharmacokinetic and safety data in 15 pediatric patients 2 to 4 years of age treated with DAYBUE [see Dosage and Administration (2.1) , Adverse Reactions (6.1) , Clinical Pharmacology (12.3) , and Clinical Studies (14) ] . Safety and effectiveness in pediatric patients less than 2 years of age have not been established. Juvenile Animal Data Oral administration of trofinetide (0, 150, 300, or 1000 mg/kg twice daily; 0, 300, 600, or 2000 mg/kg/day) to rats from postnatal day (PND) 13-14 through 28 weeks of age resulted in no adverse effects on growth or neurobehavioral function. Plasma exposures at the highest dose tested were similar to those in pediatric patients at recommended doses. Oral administration of trofinetide (0, 150, 300, or 1000 mg/kg twice daily; 0, 300, 600, or 2000 mg/kg/day) to juvenile rats for 10 weeks beginning on PND 13-14 resulted in no adverse effects on sexual maturation or reproductive function. Plasma exposures at the highest dose tested were similar to those in pediatric patients at recommended doses. 8.5 Geriatric Use Clinical studies of DAYBUE did …

12.1 Mechanism of Action The mechanism by which trofinetide exerts therapeutic effects in patients with Rett syndrome is unknown.

11 DESCRIPTION DAYBUE oral solution and DAYBUE STIX for oral solution contain the active moiety trofinetide. The chemical name of trofinetide is (2S)-2-{[(2S)-1-(2-aminoacetyl)-2-methylpyrrolidine-2-carbonyl]amino}pentanedioic acid (IUPAC). The molecular formula of trofinetide is C 13 H 21 N 3 O 6 and its molecular weight is 315.33 g/mol. The chemical structure is shown below. Trofinetide is a white to off-white solid and is freely soluble in water. DAYBUE oral solution is pink to red in color and contains 1 g of trofinetide in each 5 mL of solution (200 mg/mL). The oral solution also contains FD&C Red No. 40, maltitol, methylparaben sodium, propylparaben sodium, purified water, strawberry flavor, and sucralose as inactive ingredients. DAYBUE STIX for oral solution is a white, off-white to pinkish powder to be dissolved in a cold to room temperature water or water-based beverage before administration and contains 5,000 mg, 6,000 mg, or 8,000 mg of trofinetide in each packet. The for oral solution powder contains natural strawberry flavor and sucralose as inactive ingredients. Chemical Structure

16 HOW SUPPLIED/STORAGE AND HANDLING 16.1 How Supplied DAYBUE (trofinetide) 200 mg/mL oral solution is a pink to red, strawberry flavored solution supplied in a round high-density polyethylene (HDPE) multi-dose bottle with a child-resistant closure containing 450 mL of oral solution (NDC 63090-660-01). DAYBUE STIX (trofinetide) for oral solution is a white, off-white to pinkish powder with a strawberry flavor supplied in multi-layer aluminum packets as follows: Package Configuration and NDC Number Strength Individual Packet Carton of 60 Packets 5,000 mg 63090-663-01 63090-663-60 6,000 mg 63090-664-01 63090-664-60 8,000 mg 63090-665-01 63090-665-60 16.2 Storage and Handling DAYBUE Oral Solution Store DAYBUE in an upright position refrigerated at 2°C to 8°C (36°F to 46°F). Do not freeze. Keep the child-resistant cap tightly closed. Discard any unused DAYBUE oral solution after 14 days of first opening the bottle. DAYBUE STIX for Oral Solution Store DAYBUE STIX packets at 20°C to 25°C (68°F to 77°F); excursions permitted between 15°C and 30°C (59°F and 86°F) [see USP Controlled Room Temperature].