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Gladys Chia
Chew Yu Mei
Yvonne Teo
Cornelyus Ng
Lau Leslie

24 October 2008

11:43:00 PM

Hey people :) 2 weeks more and SIP is over! As mentioned in my previous post, I am doing in-house MP now which is developing liquid formulations of Metformin.

A Brief Introduction
Metformin is a anti-diabetic drug used to treat Type 2 Diabetes Mellitus. As Metformin tablets are only available in the market currently, I have to develop extemporaneous liquid formulations of Metformin. The concentration of the formulations are as of 0.5g/5ml. These are prepared from Metformin Tablets (500mg each) and mixed with the respective formulations in a 25ml volumetric flask. 7 formulations have been developed using Milli Q Water, Pharmaceutical Syrup and Ascorbic Acid (1%, 2% and 3%). Ascorbic Acid is an antioxidant, different concentrations are prepared so as to determine which is the better condition to prevent the degradation of Metformin. The temperature of storage are also compared between Milli Q water and Pharmaceutical syrup formulations. High Performance Liquid Chromatography (HPLC) machine will be used to assay for its stability over 30 days, which determines if degradation occurs in the formulations.

I will share with you how are the dilutions prepared. The formulations are in a concentration of 100000ppm, thus 1000x dilution is carried out to achieve 100ppm. 100ppm is the standard concentration I have chosen to assay my samples at. Each diluted formulation are assayed 3 times, so as to achieve its average peak area from the chromatograms.

MATERIALS
1. Nine 100ml volumetric flasks
2. Milli Q Water
3. 1000ul micrpipette
4. Pipette tips
5. Prepared 7 formulations
6. Shimadzu LC-20AD Machine (HPLC)
7. 1ml syringe

METHOD
1. 0.1ml of the respective formulations are pipetted out into a 100ml volumetric flask.
2. It is topped up to the mark with Milli Q water.
3. 0.5ml of the dilution is drawn out using a syringe and injected into the HPLC.

These are the 7 formulations.
#1-Milli Q water (store at 10°C)
#2-Pharmaceutical Syrup (store at 10°C)
#3-1% Ascorbic Acid (store at 10°C)
#4-2% Ascorbic Acid (store at 10°C)
#5-3% Ascorbic Acid (store at 10°C)
#6-Milli Q water (store at RT)
#7-Pharmaceutical Syrup (store at RT)

Materials used for each dilution.
For #2 and #7 (pharmaceutical syrup) formulations, 2 sets of dilution are prepared instead. Thus, a total of 6 replicates are assayed. This is because the formulation has high viscosity and it is a suspension rather than a solution. Discrepancies may occur during pipetting as Metformin is not well mixed in it.

This is the Shimadzu LC-20AD machine.

This is the area to inject the sample using a 1ml syringe. The sample is injected into the machine first...

and the knob is turned down to begin the assay.

From here, I have to process the raw data to obtain the "Percentage Remaining" value and plot the stability testing chart over 30 days. Through this chart, degradation can be observed if there is a decrease in percentage remaining.

Thats all people :) See you guys soon!
P.s Sorry about the colour, I cannot change it.

Yvonne Teo

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