1. Appearance
- The medicated Gels can be examined physically for appearance like clarity, colour and presence of any particle.
2. Skin irritation
- Skin Irritation is determined by applying the gel on the skin of healthy volunteers.
- No irritation: 0
- Slight irritation: 1
- Irritation: 2
3. pH
- pH of Gels can be measured using digital pH meter.
- Standard pH of gel is 5 to 5.5.
4. Viscosity
- Viscosity was determined using Brookefield viscometer.
5. Drug content
- Determined by appropriate spectrophotometrically like uvspectrophotometer.
6. Spreadability
- Spreadability is measured by spreading 0.5 g Gel on a circle of 2 cm diameter on a glass plate. Then a second glass plate is placed. 1/2 kg weight placed on the upper glass plate for 5 minutes.
- Finally diameter of circle spreading is measured.
S = ML/T
M= weight of an upper side
L= length of circle/ diameter
T= time in minutes
S=Spreadibility
7. Stability
- Also known as shipping test.
- It is performed to determine stability of Gel at various temperatures and RH (Relative humidity). Read more – stability Test