Lamotrigine Compounded Oral Suspension
DEFINITION
Lamotrigine Compounded Oral Suspension contains NLT 90.0% and NMT 110.0% of the labeled amount of lamotrigine (C9H7Cl2N5).
Prepare Lamotrigine Compounded Oral Suspension 1 mg/mL as follows (see Pharmaceutical Compounding—Nonsterile Preparations 
795
).
795).Place the required number of tablet(s) in a suitable mortar, and comminute to a fine powder. Add the Ora-Blend in small portions, and triturate to make a smooth paste. Add increasing volumes of the Ora-Blend to make a lamotrigine liquid that is pourable. Transfer the contents of the mortar, stepwise and quantitatively, to a calibrated bottle. Add enough of the Ora-Blend to bring to final volume, and mix well.
ASSAY
• Procedure
Solution A:
Dissolve 2.7 g of monobasic potassium phosphate in 1000 mL of water. Add 6.5 mL of triethylamine, and adjust with phosphoric acid to a pH of 2.0.
Mobile phase:
Acetonitrile and Solution A (20:80). Filter, and degas.
Diluent:
0.1 M hydrochloric acid
Standard solution:
0.4 mg/mL of USP Lamotrigine RS in Diluent
Sample solution:
Shake thoroughly each bottle of Oral Suspension. Transfer 4 mL of Oral Suspension into a 10 mL volumetric flask, dilute with Diluent to volume, and mix well.
Chromatographic system
Mode:
LC
Detector:
UV 270 nm
Column:
4.6-mm × 25-cm; 5-µm packing L1
Flow rate:
1.0 mL/min
Injection volume:
5 µL
System suitability
Sample:
Standard solution
[Note—The retention time for lamotrigine is about 9.8 min. ]
Suitability requirements
Tailing factor:
NMT 2.0
Relative standard deviation:
NMT 2.0% for replicate injections
Analysis
Samples:
Standard solution and Sample solution
Calculate the percentage of the labeled amount of lamotrigine (C9H7Cl2N5) in the portion of Oral Suspension taken:
Result = (rU/rS) × (CS/CU) × 100
| rU | = | = peak response of lamotrigine from the Sample solution |
| rS | = | = peak response of lamotrigine from the Standard solution |
| CS | = | = concentration of lamotrigine in the Standard solution (mg/mL) |
| CU | = | = nominal concentration of lamotrigine in the Sample solution (mg/mL) |
Acceptance criteria:
90.0%–110.0%
SPECIFIC TESTS
• pH 791:
4.0–5.0
791:
4.0–5.0
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Package in tight, light-resistant containers. Store at controlled room temperature or 2
–8.
–8.
• Labeling:
Label it to indicate that it is to be well-shaken before use, and to state the Beyond-Use Date.
• Beyond-Use Date:
NMT 90 days after the date on which it was compounded when stored at controlled room temperature or 2–8
–8
• USP Reference Standards 11
11
USP Lamotrigine RS 
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Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Jeanne H. Sun, Pharm.D.
Associate Scientific Liaison (301) 230-3361 |
(CMP2010) Compounding |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP38–NF33 Page 4028
Pharmacopeial Forum: Volume No. 39(4)