Accelerated Degradation Experiment
Conditions
Procedure A1: |
10 days exposure at 50 °C and 100% relative humidity. |
Procedure A2: |
20 days exposure at 50 °C and 100% relative humidity. |
Appearance of the substance
The substance, originally in the form of a white or almost white, crystalline powder, odourless or with a faint characteristic odour, changes after procedure A1 into a syrupy yellow-orange liquid, that solidifies into a sticky, viscous paste with a characteristic odour.
Gain of moisture
Before exposure to heat and humidity: |
2% |
After procedure A1: |
39% |
Chromatographic test
Adsorbent: Silica gel F-254
Solution applied to the plate: Substance dissolved in methanol.
Solvent system:
n-butanol ............. 6 volumes
acetic acid ........... 2 volumes
water ................... 2 volumes
Development conditions: The solvent is allowed to migrate until the front reaches a line 15 cm from the starting line.
Detection: The plate is left in a chromatographic chamber containing some iodine crystals until spots appear.
Results: The spots obtained from the solutions of each of the samples subjected to procedures A1 and A2, compared to the spots obtained from the reference solution of phenoxymethylpenicillin potassium are more numerous.
Ultraviolet spectrophotometry
The spectrum of a 0.025% solution of the samples subjected to procedures A1 and A2 in methanol show maxima at 263 nm, 268 nm and 274 nm. No degradation is observed.
Iodometric determination
After procedure A1: |
30% degraded |
After procedure A2: |
90% degraded |
Conclusion
Phenoxymethylpenicillin potassium is subject to decomposition under accelerated degradation conditions.
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