Nanosizing of valsartan by high pressure homogenization to produce dissolution enhanced nanosuspension: pharmacokinetics and pharmacodyanamic study

Figures & data

Table 1. Independent variables and their matching levels for nanosuspension preparation.

		Levels
Factor	Name	Low (−1)	High (+1)
A	Stabilizer concentration (w/w)	20	60
B	Cycles (numbers)	1	5
C	Pressure (bar)	500	1500
Dependent variables		Goal
Mean particle size		200–400 nm

Table 2. Twenty-three full factorial design consisting of experiments for the study of three experimental factors with experimental and predicted values.

	Coded value variables			Actual value variables				Particle size (nm)
Run	A	B	C	Stabilizer concentration (A)	Cycles (B)	Pressure (C)	Clarity (Appearance)	Actual value	Predicted value
1	+1	–1	+1	60.0	1	1500	Light milky	692.6	651.80
2	+1	+1	+1	60.0	5	1500	Slightly bluish	397.4	438.20
3	–1	–1	+1	20.0	1	1500	Milky	818	858.80
4	–1	+1	–1	20.0	5	500	Aggregate and milky	5150	5337.50
5	+1	+1	–1	60.0	5	500	Aggregate and milky	4700	4512.50
6	–1	+1	+1	20.0	5	1500	Light milky	686	645.20
7	+1	–1	–1	60.0	1	500	Aggregate and milky	9150	9337.50
8	–1	–1	–1	20.0	1	500	Aggregate and milky	10 350	10 162.50

Table 3. Percent contribution of each independent variable and their interaction on dependent variable.

Term	% Contribution	p value
A	0.468421	≥0.05
B	11.166	0.0016
C	78.7153	<0.0001
AB	0.0378614	≥0.05
AC	0.167978	≥0.05
BC	9.35281	0.0022
ABC	0.0916956	≥0.05

Figure 1. Contour plots and three-dimensional (3D) response surface plots showing the effect of number of homogenization cycles and homogenization pressure (A), concentration of stabilizer and number of homogenization cycles (B) and concentration of stabilizer and homogenization pressure on the resultant particle size (C).

Table 4. Impact of Homogenization cycles and concentration of cryoprotectant on particle size and PDI of formulations obtained by OFAT model.

Effects of homogenization cycles
Homogenization cycles	Particle size (nm)	Polydispersity index	Clarity
1	313.7	0.455	Milky
2	261.8	0.339	Light milky
3	228.4	0.373	Light milky
4	200	0.351	Milky with blue tint
5	190.5	0.206	Light milky with blue tint
Effects of cryoprotectant concentration
Concentrations (w/v)	Particle size (nm)	Polydispersity index	Clarity
1	323.4	0.538	Light milky
2	285.6	0.501	Light milky
3	250.8	0.145	Light milky
4	251.2	0.187	Light milky

Figure 2. Particle size and PDI of optimized Valsartan nanosuspensions before (A) and after (B) freeze drying.

Figure 3. TEM photograph of optimized VAL-NS formulation.

Figure 4. Comparison of saturation solubility of different formulations (p ≤ 0.005**).

Figure 5. Comparative dissolution profile of valsartan from different formulations.

Figure 6. Plasma concentrations after oral administration of micronized VAL (non-homogenized VAL) and VAL nanosuspension (VAL-NS). Here: *p ≥ 0.05 (significant), **p ≥ 0.005 (very significant), ***p ≥ 0.001 (Extremely significant).

Table 5. Comparative pharmacokinetic parameters of valsartan formulations.

Pk parameters	VAL-Susp	VAL-NS
Cmax	1384.73 ± 98.76 ng mL^−1	1627.47 ± 112.05* ng mL^−1
Tmax	3.24 ± 0.417 h	2.36 ± 0.274** h
AUC0→24	9416.24 ± 218.48 ng h  mL^−1	13279.2 ± 589.426*** ng h mL^−1
Kelim	0.105 ± 0.0327 h^−1	0.078 ± 0.008 h^−1
AUMC0→24	64372.25 ± 3508.19 ng h mL^−1	104132.8 ± 2317.56 ng h mL^−1
T1/2	6.77 ± 0.048 h	8.53 ± 0.026 h

*P ≥ 0.05 (significant), **P ≥ 0.005 (very significant), ***P ≥ 0.001 (Extremely significant).

Figure 7. Comparative BP of control, hypertensive control, non-homogenized valsartan suspension and valsartan nanosuspension (VAL-NS) treated groups at different time intervals. Here: *p ≥ 0.05 (significant), **p ≥ 0.005 (very significant), ***p ≥ 0.001 (Extremely significant).

Figure 8. Particle size distribution showing physical stability (A) whereas drug assay showing the chemical stability (B) of the optimized formulation (VAL-NS).