Doxycycline Hyclate Capsules

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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1 DEFINITION

Doxycycline Hyclate Capsules contain the equivalent of NLT 90.0% and NMT 120.0% of the labeled amount of doxycycline (C₂₂H₂₄N₂O₈).

2 IDENTIFICATION

A. The retention time of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

B. SPECTROSCOPIC IDENTIFICATION TESTS (197), Infrared Spectroscopy: 1974

Standard solution: Transfer about 25 mg of USP Doxycycline Hyclate RS to a suitable flask. Add 25 mL of acetonitrile and mix for approximately 5 min with a magnetic stir bar. Pass the solution through a suitable filter, and remove the solvent by natural evaporation or by using a rotary evaporator under vacuum.

Sample solution: Transfer the contents of NLT 10 Capsules, equivalent to 25 mg of doxycycline hyclate, to a suitable flask. Add 25 ml. of acetonitrile and mix for approximately 5 min with a magnetic stir bar. Pass the solution through a suitable filter, and remove the solvent by natural evaporation or by using a rotary evaporator under vacuum.

Analysis: Examine the spectra of the Standard solution and the Sample solution in the range between 2000 and 650 cm

Acceptance criteria: The Sample solution exhibits bands at about 1663, 1611, 1576, 1453, 1213, 1037, 1002, 935, and 659 cm, similar to the Standard solution.

3 ASSAY

PROCEDURE

Protect solutions containing doxycycline from light.

Solution A: Transfer 3.1 g of monobasic potassium phosphate, 0.5 g of edetate disodium, and 0.5 ml. of triethylamine to a 1000-mL volumetric flask. Add about 850 mL of water and mix. Dilute with water to volume and adjust with 1 N sodium hydroxide VS to a pH of 8.5 0.2.

Solution B: Methanol

Mobile phase: See Table 1

Diluent: 0.01 N hydrochloric acid

System suitability stock solution 1: 1 mg/mL each of USP Doxycycline Related Compound A RS and USP Methacycline Hydrochloride RS in Diluent

System suitability stock solution 2: 1.2 mg/mL of USP Doxycycline Hyclate RS in Diluent

System suitability solution: Transfer 5 mL of System suitability stock solution 2 to a 25-mL volumetric flask, heat on a steam bath for 60 min, and evaporate to dryness on a hot plate, taking care not to char the residue. Dissolve the residue in Diluent, add 0.5 mL of System suitability stock solution 1, and dilute with Diluent to volume. Pass the solution through a suitable filter and use the filtrate.

This solution contains a mixture of 4-epidoxycycline, doxycycline related compound A, methacycline, and doxycycline. When stored in a refrigerator, this solution may be used for 14 days.

Standard solution: 0.3 mg/mL of USP Doxycycline Hyclate RS in Diluent. Sonicate as needed to dissolve.

Sample solution: Nominally 0.25 mg/mL of doxycycline in Diluent, prepared as follows. Empty as completely as possible the contents of NLT 20 Capsules. Mix the combined contents and transfer a suitable portion of the powder to a suitable volumetric flask. Add 75% of the final. volume of Diluent, sonicate for about 5 min, shake for about 15 min, and dilute with Diluent to volume. Pass a portion of this solution through a suitable filter of 0.2-µm pore size.

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 350 nm

Column: 2.1-mm x 5-cm; 1.7-um packing LZ. [NOTE-A 1.7-um guard column with packing 17 was used during method validation.]

Column temperature: 60°

Flow rate: 0.6 mL/min

Injection volume: 5 µL

System suitability

Samples: System suitability solution and Standard solution

[NOTE-See Table 2 for relative retention times.]

Suitability requirements

Resolution: NLT 1.5 between methacycline and 4-epidoxycycline; NLT 1.5 between 4-epidoxycycline and doxycycline related compound A; NLT 1.5 between doxycycline related compound A and doxycycline, System suitability solution

Tailing factor: NMT 1.5, Standard solution

Relative standard deviation: NMT 2.0%, Standard solution

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of doxycycline (CHN₂O) in the portion of Capsules taken:

Result = (r_U/(r_S) × (C_S /C_U) × P x F x 100

r_U = peak response from the Sample solution

r_S = peak response from the Standard solution

C_S = concentration of USP Doxycycline Hyclate RS, in the Stardard solution (mg/ml)

C_U = nominal concentration of doxycycline in the Sample sulation (mg/ml)

P = potency of doxycycline in USP Doxycycline Hyclate RS (µg/mg)

F = conversion factor 0.001 mg/μg

Acceptance criteria: 90.0%-120.0%

PERFORMANCE TESTS

DISSOLUTION (711)

Medium: Water, 900 mL

Apparatus 2: 75 rpm, the distance between the blade and the inside bottom of the vessel being maintained at 4.5 ± 0.5 cm during the test

Time: 30 min

Standard solution: USP Doxycycline Hyclate RS in Medium

Sample solution: Dilute with Medium to a concentration that is similar to the Standard solution.

Instrumental conditions

Mode: UV

Analytical wavelength: 276 nm

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage (Q) of the labeled amount of doxycycline(C₂₂H₂₄N₂O₈) dissolved:

Result = (A_U/A_S) x (CS/L) x V x 100

A_U = absorbance of the Sample solution

A_S = absorbance of the Standard solution

CS = 1 concentration of doxycycline in the Standard solution (mg/mL)

L = label claim (mg/Capsule)

V = volume of Medium, 900 mL

Tolerances: NLT 80% (Q) of the labeled amount of doxycycline (C₂₂H₂₄N₂O₈) is dissolved.

UNIFORMITY OF DOSAGE UNITS (905): Meet the requirements

4 IMPURITIES

ORGANIC IMPURITIES

Mobile phase, Diluent, System suitability solution, Sample solution, and Chromatographic system: Proceed as directed in the Assay

Standard solution: 1.5 µg/mL of USP Doxycycline Hyclate RS in Diluent

System suitability

Samples: System suitability solution and Standard solution

Suitability requirements

Resolution: NLT 1.5 between methacycline and 4-epidoxycycline; NLT 1.5 between 4-epidoxycycline and doxycycline related compound A NLT 1.5 between doxycycline related compound A and doxycycline, System suitability solution

Relative standard deviation: NMT 5.0% for the doxycycline peak, Standard solution

Analysis

Samples: Sample solution and Standard solution

Calculate the percentage of each impurity in the portion of Capsules taken:

Result = (r_U/(r_S) × (C_S /C_U) × P x F x 100

r_U = peak response from the Sample solution

r_S = peak response from the Standard solution

C_S = concentration of USP Doxycycline Hyclate RS, in the Stardard solution (mg/ml)

C_U = nominal concentration of doxycycline in the Sample sulation (mg/ml)

P = potency of doxycycline in USP Doxycycline Hyclate RS (µg/mg)

F = conversion factor 0.001 mg/μg

Acceptance criteria: See Table 2 Disregard any impurity peaks less than 0.2%

^a (4S,4aR,55,5aR, 12aS)-4-(Dimethylamino)-1,4,4,5,58,6,11,12a-octahydro-3,5,10,12,12a-pentahydroxy-6-methylene-1,11-dioxo-2-naphthacenecarboxamide.

^b (4R,4aR,55,5aR,6,12aS)-4-(Dimethylamino)-1,4,4,5,5a,6,11,12a-octahydro-3,5,10,12,12a-pentahydroxy-6-methyl-1,11-dioxo-2-naphthacenecarboxamide.

^c(4R,4aR,5S,5aR,6R,12aS)-4-(Dimethylamino)-1,4,4a,5,5a,6,11,12a-octahydro-3,5,10,12,12a-pentahydroxy-6-methyl-1,11-dioxo-2- naphthacenecarboxamide.

^d (4S,4aR,5S,5aR,6S,12aS)-4-(Dimethylamino)-1,4,4a,5,5a,6,11,12a-octahydro-3,5,10,12,12a-pentahydroxy-6-methyl-1,11-dioxo-2-naphthacenecarboxamide.

5 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Preserve in tight, light-resistant containers. Store at controlled room temperature.