Dear colleagues,
I have dedicated this week’s topic once again to a widely discussed preparation. This preparation, which we frequently compound in our pharmacies, is one of the most prominent examples of saturated solutions, known as SATURATED SOLUTION.
Let us examine together the breakdown of the formula prepared by pharmacy students in France.
Rp
Acide borique ………….. 5.00 to 6.00 g
Alcool 70 % v/v ………………. 100.00 g
Active substances included in the formula;
Boric acid-Acido borico-Borsaure-ACIDUM BORICUM TK. 1974 (Pages 16-17) Boric acid is a drug with weak bacteriostatic and fungistatic effects. The exact mechanism of the antibacterial and antifungal effects of boric acid is unknown. Boric acid exhibits a slow bacteriostatic effect against staphylococci and streptococci. It dissolves in 25 parts of water, 3 parts of boiling water, 16 parts of ethanol (95%) R, and 5 parts of glycerol (85%) R.
Aethanolum-Alcoholum-Ethanolum-Spiritus vini: In ancient times, it was called the “water of life” and was practically believed to be a cure for almost every illness. An important property of alcohol is that it is an excellent solvent frequently used in most pharmaceutical formulations. While ethyl alcohol is effective at concentrations of 60-90%, a 70% concentration (vol/vol) provides optimal efficacy for skin antisepsis. In contrast, when the concentration falls below 50%, it largely loses its activity.
Alcohol exerts its effect by coagulating proteins and dissolving lipids. Since protein denaturation requires the presence of some water, the antimicrobial effect of absolute (96%) alcohol is weak.
What is a SATURATED SOLUTION?
“If an excess amount of a solid substance is placed in a liquid and stirred and shaken under the condition of maintaining a specific temperature, some molecules of the solid disperse among the liquid molecules. This dispersion continues until an equilibrium is established between the dispersed molecules of the solid substance and its undispersed molecules. Thus, a solution in which an equilibrium has been established between the dissolved particles and the undissolved particles is called a saturated solution-(SATURATED SOLUTION).”
As seen in this formula, since 1 part of boric acid is known to dissolve easily in 25 parts of alcohol, it has been calculated that a saturated solution in 70% v/v alcohol can be prepared using slightly more than 4 grams of boric acid.
Preparation
Although it is possible to dissolve the boric acid in the calculated amount of alcohol by triturating it in a glass mortar, boric acid dissolves more easily in a warm environment. Heat accelerates dissolution.
Therefore, by slightly increasing the temperature (25-30 °C), we enhance dissolution.
70% alcohol is prepared, then boric acid is added to the alcoholic solvent inside an Erlenmeyer flask in a hot water bath and heated up to 25-30 degrees on a magnetic stirrer. The reaction is irreversible. The solution is filtered, and any lost volume is made up with 70% v/v alcohol. Wetting the filter paper to be used in filtration with 70% v/v alcohol prior to the filtration process is important in terms of minimizing solution loss.
Wishing you a good week…
Specialist Pharmacist Ahmet Nezihi Pekcan
Pekcan Pharmacy – Konya
[email protected]
Tel: (332) 3520657
http://www.majistralformul.com/
