Test Method for Doxycycline Capsule 100mg

Doxycycline is a bacteriostatic antibiotic with a broad spectrum of action against a wide range of anaerobic gram-positive and gram-negative bacteria including penicillin-resistant strains. It also has anti-microbial activity against chlamydia, mycoplasmas, rickettsia, spirochetes and also some protozoa.
Doxycycline is believed to exert its pharmacological action by inhibiting protein synthesis of susceptible micro-organisms.

Each Capsule Contains:
Doxycycline Hyclate equivalent to Doxycycline . . . . 100mg

Visually examine the representative number of capsules for colour, shape, markings & the presence of foreign matter.

Triturate 1-2 mg of capsule powder with 300 - 400mg of finely powdered and dried potassium bromide. Carefully grind the mixture, spread it uniformly in a suitable die, and submit it to a pressure to form a transparent disc. Carefully place the disc in disc holder & placed in IR spectrophotometer. Record the absorption spectrum.

Average fill weight
Weigh the content of 20 capsules & find out the average fill weight.

Uniformity of Fill Weight
  • Select 20 capsules at random from the sampled lot.
  • Determine the weight of one of the twenty capsules. Open it and empty the contents as completely as possible into a tarred vessel; weigh and record the net content.
  • Repeat the above step for the remaining 19 capsules.
  • Calculate the Uniformity of Fill Weight using following formula.

  • Place 1 capsule in each of the 6 tubes of the basket & cover with disc. Operate the apparatus using water, maintained at 37 ± 2°C, as the immersion fluid. At the end of the specified time, lift the basket from the fluid & observe the dosage units. All of the dosage unit disintegrate completely.
  • Note: Disintegration is considered to be complete when no residue except fragments of the capsule shell remains on the screen of the test apparatus.

Medium : 0.01 N hydrochloric acid ; 900 mL
Apparatus : II ( Paddle )
Speed : 75 RPM
Time : 60 minutes.
Temperature : 37°C ± 0.5°C

Place 900mL of dissolution medium maintained at 37 ± 0.5°C in 6 dissolution vessels separately & fix in the dissolution bath. Place 1 capsule into each of six basket & fix the basket to the shaft, bring it into the position. Operate the instrument at 75 RPM for 60 min. At the end of 60 min, Withdraw 5mL of sample of the medium & dilute to 50mL with dissolution medium. Filter through 0.45µ filter. Measure the absorbance at 268nm.

Standard Solution:
Weigh 55mg of Doxycycline Hyclate SRS 100mL volumetric flasks, add 70mL of dissolution media to dissolve & dilute with same to volume. Dilute 2mL of this solution to 100mL with dissolution media.

Calculate the percentage of labeled amount dissolved:

Chromatographic Conditions:
Column : 250 × 4.6 mm, 5 µm, C18
Flow Rate : 1.0 mL/minute
Column Temperature : 25°C
Detection Wavelength : 254 nm
Injection Volume : 50 µL

Preparation of 0.2 M potassium dihydrogen phosphate:
Dilute 6.81 g potassium dihydrogen phosphate in 250 mL with water.

Preparation of Buffer:
250 mL of 0.2 M potassium dihydrogen phosphate solution, adjust pH 5.0 with dilute sodium hydroxide solution and dilute to 1000 mL with water.

Preparation of Mobile phase:
Mix 200 mL of acetonitrile and 800 mL of buffer. Degas and filter the mixture.

Standard Preparation:
Transfer about 70 mg of Amoxicillin trihydrate working standard in 100mL volumetric flask, add 80mL of mobile phase, sonicate to dissolve and make up to the mark with mobile phase. Transfer 5 mL of this solution to 50 mL mobile phase.

Sample Preparation:
Transfer about 73.1 mg of capsule powder in 100mL volumetric flask, add 80mL of mobile phase, sonicate to dissolve and make up to the mark with mobile phase. Transfer 5 mL of this solution to 50 mL mobile phase.

The test is not valid unless the RSD for replicate injections is NMT2.0%


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