Levalbuterol Hydrochloride
(lev'' al bue' ter ol hye'' droe klor' ide).
Click to View Image

C13H21NO3·HCl 275.77
(R)-1-[(tert-Butylamino)methyl]-4-hydroxy-m-xylene-,¢-diol hydrochloride     [50293-90-8].
DEFINITION
Levalbuterol Hydrochloride contains NLT 98.0% and NMT 102.0% of C13H21NO3·HCl, calculated on the anhydrous basis.
IDENTIFICATION
ASSAY
•  Procedure
Solution A:  1 in 1000 solution of phosphoric acid in water
Solution B:  Acetonitrile, methanol, phosphoric acid, and water (350:350:1:300)
Mobile phase:  See the gradient table below.
Time
(min)
Solution A
(%)
Solution B
(%)
0 91.5 8.5
15 91.5 8.5
15.01 0 100
20 0 100
20.01 91.5 8.5
30 91.5 8.5
Diluent:  Solution A
Standard solution:  100 µg/mL of USP Levalbuterol Hydrochloride RS in Diluent
Sample solution:  100 µg/mL of Levalbuterol Hydrochloride in Diluent
Chromatographic system 
Mode:  LC
Detector:  UV 220 nm
Column:  4.6-mm × 15-cm; 5-µm packing L1
Column temperature:  35
Flow rate:  1 mL/min
Injection size:  10 µL
System suitability 
Sample:  Standard solution
Suitability requirements 
Column efficiency:  Greater than 5500 theoretical plates
Tailing factor:  Less than 2.3
Relative standard deviation:  NMT 2.0%
Analysis 
Samples:  Standard solution and Sample solution
Calculate the percentage of C13H21NO3·HCl in the portion of Levalbuterol Hydrochloride taken:
Result = (rU/rS) × (CS/CU) × 100
rU== peak response of levalbuterol hydrochloride from the Sample solution
rS== peak response of levalbuterol hydrochloride from the Standard solution
CS== concentration of USP Levalbuterol Hydrochloride RS in the Standard solution (µg/mL)
CU== concentration of the Sample solution (µg/mL)
Acceptance criteria:  98.0%–102.0% on the anhydrous basis
IMPURITIES
Inorganic Impurities 
•  Residue on Ignition 281: NMT 0.1%
•  Heavy Metals, Method I 231: NMT 10 ppm
Organic Impurities 
•  Procedure 1
Solution A, Solution B, Diluent, and Sample solution:  Proceed as directed in the Assay.
Standard solution:   [Note—Prepare a solution containing the following in Diluent. ]
USP Levalbuterol Hydrochloride RS, 100 µg/mL
USP Levalbuterol Related Compound A RS, 0.05 µg/mL
USP Levalbuterol Related Compound B RS, 0.05 µg/mL
USP Levalbuterol Related Compound C RS, 0.05 µg/mL
USP Levalbuterol Related Compound D RS, 0.05 µg/mL
USP Levalbuterol Related Compound E RS, 0.05 µg/mL
USP Levalbuterol Related Compound F RS, 0.05 µg/mL
USP Levalbuterol Related Compound H RS, 0.05 µg/mL
Mobile phase:  See the gradient table below.
Time
(min)
Solution A
(%)
Solution B
(%)
0 100 0
30 70 30
50 28 72
50.01 0 100
55 0 100
55.01 100 0
70 100 0
Chromatographic system 
Mode:  LC
Detector:  UV 220 nm
Column:  4.6-mm × 15-cm; 5-µm packing L1
Column temperature:  45
Flow rate:  1 mL/min
Injection size:  50 µL
System suitability 
Sample:  Standard solution
Suitability requirements 
Resolution:  NLT 4.9 between levalbuterol and levalbuterol related compound A; NLT 1.5 between levalbuterol related compound B and levalbuterol related compound C
Column efficiency:  NLT 4000 for levalbuterol
Tailing factor:  NMT 4.0 for levalbuterol
Relative standard deviation:  Less than 20% from any of the six related compound peaks
Analysis 
Samples:  Standard solution and Sample solution
[Note—Integrate all peaks with an area greater than 0.05% of the area corresponding to the levalbuterol peak. ]
Calculate the percentage of each impurity in the portion of Levalbuterol Hydrochloride taken:
Result = (rU/rT) × (1/F) × 100
rU== peak response of each impurity from the Sample solution
rT== sum of the responses of all the peaks
F== relative response factor for each impurity (see Impurity Table 1)
Acceptance criteria:  See Impurity Table 1.
Impurity Table 1
Name Relative
Retention
Time
Relative
Response
Factor
Acceptance
Criteria,
NMT (%)
Levalbuterol related compound A 1.2 1.0 0.1
Levalbuterol related compound H 1.3 1.0 0.15
Levalbuterol related compound B 1.5 1.0 0.10
Levalbuterol related compound C 1.6 1.0 0.15
Levalbuterol related compound D 1.7 3.0 0.05
Levalbuterol related compound E 2.1 1.0 0.1
Levalbuterol related compound F 3.5 1.2 0.10
Any unknown impurity 0.10
Total unknown impurities 0.1
Total impurities 0.5
•  Procedure 2: Enantiomeric Purity and Chiral Identity
Mobile phase:  Acetonitrile, methanol, acetic acid, and triethylamine (500:500:3:1)
Diluent:  Mobile phase
System suitability solution A:  0.10 mg/mL of USP Levalbuterol Hydrochloride RS and 0.40 µg/mL of USP Albuterol RS in Diluent
System suitability solution B:  1.5 mg/mL of USP Albuterol RS in Diluent
Sample solution:  0.8 mg/mL of Levalbuterol Hydrochloride in Diluent
Chromatographic system 
Mode:  LC
Detector:  UV 225 nm
Column:  4.6-mm × 25-cm; 5-µm packing L63
Flow rate:  1 mL/min
Injection size:  10 µL
System suitability 
Sample:  System suitability solution A
Suitability requirements 
Resolution:  NLT 2.0 between levalbuterol and (S)-albuterol
Column efficiency:  NLT 4000, calculated from either peak
Tailing factor:  NMT 2.2 for levalbuterol and (S)-albuterol
Relative standard deviation:  NMT 20% for (S)-albuterol, injected three times
Analysis 
Samples:  System suitability solution B and Sample solution
Calculate the percentage of (S)-albuterol in the portion of Levalbuterol Hydrochloride taken:
Result = (rU/rT) × 100
rU== peak response of (S)-albuterol
rT== sum of the peak responses for both levalbuterol and (S)-albuterol
Acceptance criteria:  NMT 0.2% of (S)-albuterol
SPECIFIC TESTS
•  Microbial Enumeration Tests 61 and Tests for Specified Microorganisms 62: The total aerobic bacterial count is less than 10 cfu/g. The total combined molds and yeasts count is less than 10 cfu/g. It meets the requirements of the tests for absence of Salmonella species, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa.
•  pH 791: 4.5–5.5, in a 10-mg/mL solution
ADDITIONAL REQUIREMENTS
•  Packaging and Storage: Preserve in tight, light-resistant containers, and store at controlled room temperature.
•  USP Reference Standards 11
USP Albuterol RS Click to View Structure
USP Levalbuterol Hydrochloride RS Click to View Structure
(R)-1-[(tert-Butylamino)methyl]-4-hydroxy-m-xylene-,¢-diol hydrochloride.
USP Levalbuterol Related Compound A RS Click to View Structure
4-(2-tert-Butylamino-ethyl)-2-hydroxymethyl-phenol.
USP Levalbuterol Related Compound B RS Click to View Structure
[{(1,1-Dimethylethyl)amino}methyl]-4-hydroxy-3-methyl-benzenemethanol.
USP Levalbuterol Related Compound C RS Click to View Structure
[{(1,1-Dimethylethyl)amino}methyl]-4-hydroxy-3-(methoxymethyl)-benzenemethanol.
USP Levalbuterol Related Compound D RS Click to View Structure
5-[2-{(1,1-Dimethylethyl)amino]-1-hydroxyethyl]-2-hydroxy-benzaldehyde.
USP Levalbuterol Related Compound E RS Click to View Structure
[{(1,1-Dimethylethyl)amino}methyl]-3-(ethoxymethyl)-4-hydroxy-benzenemethanol.
USP Levalbuterol Related Compound F RS Click to View Structure
[{(1,1-Dimethylethyl)amino}methyl]-4-(phenylmethoxy)-1,3-benzenedimethanol.
USP Levalbuterol Related Compound H RS
4-[2-(tert-Butylamino)-1-methoxyethyl]-2-(hydroxymethyl)phenol.
    C14H23NO3        253.34
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Ravi Ravichandran, Ph.D.
Principal Scientific Liaison
1-301-816-8330
(SM42010) Monographs - Small Molecules 4
61 Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison
1-301-816-8339
(GCM2010) General Chapters - Microbiology
62 Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison
1-301-816-8339
(GCM2010) General Chapters - Microbiology
Reference Standards RS Technical Services
1-301-816-8129
rstech@usp.org
USP35–NF30 Page 3654
Pharmacopeial Forum: Volume No. 36(3) Page 670