It is possible to enlarge and reduce formulas in prescriptions using different calculation methods.Cold cream-Unguentum Leniens-Cold cream T.K. (1954)
Rp.
White beeswax 7 g
Spermaceti 8 g
Almond oil 60 g
Water 25 g
Rose essence 0.1 g
The weight of the preparation to be prepared is 100.1 grams. Calculations should be made based on this weight.
Ingredient quantities to be taken for 30 grams of preparation requested in the prescription;
White beeswax : 7×30:100.1 = 2.09 g
Spermaceti : 8×30:100.1 = 2.39 g
Almond oil : 60×30:100.1= 17.98 g
Water : 25×30:100.1 = 7.49 g
Rose essence : 0.1×30:100.1= 0.02 g.
Work the given formula at a ratio of (1/3).
White beeswax : 7×1:3= 2.33 g
Spermaceti : 8×1:3= 2.66 g
Almond oil : 60×1:3 = 20 g
Water : 25×1:3 = 8.33 g
Rose essence : 0.1×1:3= 0.03 g.
Pharmaceutical preparations can be prepared in amounts less than or greater than the quantities specified in their formula. The required amounts of ingredients for the formula can be scaled up or scaled down within a specific ratio.
This ratio is: Dividing the amount of preparation to be prepared / By the total weight of the formula. The formula is calculated using the constant found here. If this value is greater than the number (1), it is called the enlargement = scaling-up factor; if it is less than the number (1), it is called the reduction = scaling-down factor.
Example formula;
Rp.
Menthol 0.01 g
Camphor 2 g
Zinc oxide 5 g
Starch 10 g
Talc q.s.p. 40 g
Prepare 20 g.
Calculation; 20/40 = 0.5 is found as the reduction factor. By multiplying the values given in the formula by the constant 0.5, the amounts of ingredients required in the prescription are determined.
Menthol 0.01×0.5= 0.005 g
Camphor 2×0.5= 1 g
Zinc oxide 5×0.5= 2.5 g
Starch 10×0.5= 5 g
Talc q.s.p. 40×0.5= 20 g.
If the same formula is requested to be prepared as 80 g;
Calculation; 80/40= 2 is found as the scaling-up factor. By multiplying the values given in the formula by the constant 2, the amounts of ingredients required in the prescription are determined.
Menthol 0.01×2= 0.02 g
Camphor 2×2= 4 g
Zinc oxide 5×2= 10 g
Starch 10×2= 20 g
Talc q.s.p. 40×2= 80 g.
Wishing you a good week…
Exp. Pharm. Ahmet Nezihi Pekcan
Pekcan Pharmacy – Konya
[email protected]
Tel: (332) 3520657http://www.majistralformul.com/
