247 Magnesium Myristate
conventional excipients showed viscosity in the range from 2,608 ± 6.50 to 2,880 ± 23.06
cps, while liquid foundation using magnesium myristate showed viscosity in the range
from 2,618 ± 6.55 to 3,304 ± 15.04 cps. The results have been depicted in Figure 1.
Spreadability. The spreadability of the formulated product was determined to assess if it
spreads well when applied to the skin. Good topical preparation has a spreadability of 7–31
gm.cm./sec. The spreadability of liquid foundation using conventional excipients was found
from 6.33 ± 0.14 to 7.12 ± 0.12 gm.cm./sec, while the spreadability of liquid foundation
using magnesium myristate was found in the range from 6.41 ± 0.144 to 8.18 ± 0.288
gm.cm./sec. The results have been depicted in Figure 2.
OPTIMIZATION OF LIQUID FOUNDATION USING CONVENTIONAL EXCIPIENTS
Design-Expert® software (Stat-Ease, Inc., Minnesota, USA) projected a total eight
experimental runs from the 23 factorial design for the three components: stearic acid (X1),
Table VI
Preformulation Parameters of Magnesium Myristate Powder
Parameters Result Flow property
Bulk density (g/ml) 0.436 ± 0.011 Excellent Flow
Tapped density (g/ml) 0.573 ± 0.025
Carr’s index (%)10.88 ± 2.671
Hausner ratio 1.13 ± 0.036
Angle of repose (°) 24.204° ± 1.645
Loss on drying (%)0.019 ± 0.000
Figure 1. Viscosity of liquid foundation using magnesium myristate and conventional excipients.

248 JOURNAL OF COSMETIC SCIENCE
PGM (X2), and dimethicone (X3), which were modified at three distinct levels (coded as -1,
0, and 1). The response parameters of viscosity (Y1) and spreadability (Y2) were examined.
ANOVA was used to estimate the quantitative effects of the variables. Data analysis
produced a quadratic model. Model terms are considered significant when p 0.05. The
residual equations in terms of coded factors for two dependent variables are shown below.
For dependent variable 1 (viscosity):
Viscosity 2,754.00 73.00 A B =+-18.00 × × (eq. 9)
For dependent variable 2 (spreadability):
Spreadability A C =-+6 68 0.2238 0.0937 .× × (eq. 10)
The relevant factors were identified as stearic acid concentration (X1), PGM concentration
(X2), and dimethicone (X3), all of which had a synergistic influence on the response Y1 and
Y2 with p values of 0.0124 and 0.0452, respectively.
The response surface graph (Figure 3A) indicates an increase in viscosity with an increase
in the concentration of both stearic acid and propylene glycol monostearate. Figure 3B
indicates an increase in spreadability with an increase in the concentration of dimethicone
and a decrease in the concentration of stearic acid.
The ideal values for the responses were determined using numerical analysis based on the
desirability criterion. The optimal stearic acid, PGM, and dimethicone concentrations have
been found to be 2.01%, 2.24%, and 6%, respectively.
Figure 2. Spreadability of liquid foundation using magnesium myristate and conventional excipient.