| الملخص | Abstract
This work has been carried out to develop national drug product contains (2 %) erythromycin as gel, it is used for the treatment of acne .
Several gel formulations were prepared using different gels bases , preservatives and humectants. Selection of best formula relied solely
on physicochemical testing of sample exposed to thermal stresses.
Stability study was conducted on the product for (6) months at different temperatures to determine the expiration date and the best storage conditions.
We obtained an antibiotic gel used to treat acne vulgaris of good homogeneity, softness and adhesivity.
The expiry date calculated to be not less than (2) years.
Keywords:- Erythromycin, Acne, Topical gel .
Introduction
Acne vulgaris is one of the commonest skin disorders which dermatologists have to treat, mainly affect adolescents, though it may present at any age . Acne by definition is multifactorial chronic inflammatory disease of pilosebaceous units [1].
Effective pharmaceutical ingredients must be formulated in a suitable dosage form to enable the patient to get active and safe drug with good features. Erythromycin gel is a generic drug not manufactured in the Iraqi factories, Therefore, the aim of this study is a necessary to have an Iraqi formula for this dosage form with its stability study compatible with specifications of united state pharmacopeia. This study is considered one of the important documents for the purposes of registration in the ministry of health. Erythromycin gel for topical dermatological use. Erythromycin is a macrolide antibiotic produced from a strain of Saccaropolyspora erythraea (formerly Streptomyces erythreus). It is a base and readily forms salts with acids. The drug works through stopping the growth of bacteria. Gel formulations contain a large amount of alcohol which dries extra oils from the skin [2].
Erythromycin gel used to treat acne by slowing the growth of bacteria on the skin, which causes the disease [3].
Erythromycin acts by inhibition of protein synthesis in susceptible organisms by reversibly binding to (50) S ribosomal subunits, thereby inhibiting translocation of amino acyl transfer-RNA and inhibiting polypeptide synthesis[3].
Erythromycin is a white or slightly yellow powder or colourless or slightly yellow crystals, slightly hygroscopic, slightly soluble in water (the solubility decreases as the temperature rises), freely soluble in ethanol (96 per cent), soluble in methanol [4].
Materials and methods :
The formula contains erythromycin (2 %) as active ingredient and carbopol 940, triethanolamine, ethanol (96 %), methyl paraben, propyl paraben and purified water as inactive ingredients.
Sufficient quantity of carbopol (940) was distributed on to warm water with continuous stirring. The dispersion was set aside for (2 h),then the erythromycin and other ingredients were added subsequently with continuous stirring .The volume was adjusted with distilled water and the dispersion were neutralized to pH (5.5) .The formula was sonicated for (20 min) to get rid of air bubbles and filled in a (25 g) aluminum lacquer tube.
Stability study:
Stability study was conducted on the product for (6) months at different temperatures (room temperature,40,50,60) ◦C to determine the expiration date and the best storage conditions by relied on physicochemical and assay testing of the selected formula.
Results and discussion
Different formulas of gels were prepared according to the specification of united state pharmacopeia 2010.
Visual examination of the prepared erythromycin gel formulated was observed and it's found to be translucent homogenous and of acceptable thickness , and Texture. The (pH) measurements were done by using a digital type of pH meter by dipping the glass electrode into the gel. And it's found to be similar skin pH (5.5) that will not hurt the skin. Stability studies of the selected formula at different temperatures are presented in tables (2) , (3) and (4).
The result of stability study showed that the prepared erythromycin topical gel has a good stability in the antibiotics – microbial assays at different temperatures (R.T, 40, 50, and 60) ◦C.
According to this study, the expiration date has been estimated to be not less than( 2) years from the date of manufacturing at room temperature.
Table -1-the physico-chemical changes of Erythromycin topical gel (2 %) with time at different temperatures.
Storage time (month) Temp. % of Erythromycin pH
(4-7) appearance
Zero time R.T 103.8 5.7 Homogenous transparent gel
1 RT 103.7 5.7 = = =
40 C° 102.6 5.7 = = =
50 C° 102 5.7 = = =
60 C° 101.1 5.7 = = =
2
RT 103 5.7 = = =
40 C° 101.18 5.6 = = =
50 C° 101.58 5.6 = = =
60 C° 100.24 5.6 = = =
3
RT 103 5.6 = = =
40 C° 102.1 5.6 = = =
50 C° 101.2 5.5 = = =
60 C° 99.58 5.5 = = =
4
RT 102.8 5.6 = = =
40 C° 101.8 5.5 = = =
50 C° 100.7 5.5 = = =
60 C° 98.75 5.5 = = =
5
RT 102.5 5.6 = = =
40 C° 101.73 5.5 = = =
50 C° 100.35 5.5 = = =
60 C° 98 5.5 = = =
6
RT 102.1 5.6 = = =
40 C° 101.88 5.5 = = =
50 C° 99.96 5.5 = = =
60 C° 97.3 5.5 = = =
Table - 2 -the stability of Erythromycin topical gel, concentration of Erythromycin at zero time =103.8 of the label amount
Concentration at 60 C°)) Concentration at
(50 C°) Concentration at
(40 C°) Concentration at (R.T) Time /day
103.8 103.8 103.8 103.8 30
101.1 102 102.6 103.7 60
100.24 101.58 102.18 103.3 90
99.58 101.2 102.1 103 120
98.75 100.7 101.8 102.8 150
98 100.35 101.73 102.5 180
Regarding the expiry date of the prepared formula we followed the Zero – order rate of reaction that is expected for kinetic of erythromycin topical gel particularly in the first stage of reduction of concentration.
T90% =0.1C/K
Where:
C=concentration at zero time
K= rate of reaction
T= time (day)
Table -3- The (T90%) at different temperatures.
T90%Year T90% day Temp.
2.98 1090 R.T
2.7 993 40C°
1.52 555 50C°
0.878 320 60C°
References
1- Sanjay K Rathi. Acne vulgaris treatment. Indian J Dermatol. 2011 Jan- Feb; 56(1): 7–13.
2- Vyas Jigar, Gajjar Vishal, Gediya Tejas, Christian Vishal, Upadhyay Umesh. Formulation and characterization of topical gel of erythromycin entrapped into niosomes . International Journal of PharmTech Research. Vol.3, No.3, pp. 1714-1718, July-Sept 2011. 3- Jp Remon. The formulation and stability of erythromycin benzoyl peroxide in a topical gel. International Journal of Pharmaceutics. 03/1999; 178(1):137-41.
4- British Pharmacopoeia press, 2013, British Pharmacopoeia, U.K. | en_US |
