Dual Drug Loaded Lipid Nanocarrier Formulations for Topical Ocular Applications

Figures & data

Table 1 Effect of Different Concentrations of Polysorbate 80 on Particle Size, Polydispersity Index, and Zeta Potential of Different NLC Placebos (Mean ± SD, n = 3)

Formulation Composition (%w/v)	P1	P2	P3	P4	P5	P6	P7	P8
Glyceryl distearate	3.0	3.0	3.0	3.0	3.0	3.0	3.0	3.0
Oleic acid	1.0	1.0	1.0	1.0	–	–	–	–
Castor oil	–	–	–	–
Polysorbate 80	0.75	1.0	1.5	2.0	0.75	1.0	1.5	2.0
Poloxamer 188	0.25	0.25	0.25	0.25	0.25	0.25	0.25	0.25
Glycerin	2.25	2.25	2.25	2.25	2.25	2.25	2.25	2.25
Water up to (mL)	10	10	10	10	10	10	10	10
Particle size (nm)	384.4±7.9	291.6±10.4	211.7±4.5	142.3±3.9	420.2±12.2	352.5±5.4	261.3±6.5	225.2±10.2
Polydispersity index	0.41±0.06	0.42±0.08	0.39±0.02	0.38±0.01	0.55±0.07	0.55±0.02	0.59±0.03	0.57±0.09
Zeta potential (mV)	−28.5±1.5	−29.6±0.7	−31.4 ±1.3	−27.1±1.7	−29.2±1.5	−27.4±1.7	−32.3±1.3	−31.6±1.1

Abbreviation: P, placebo.

Table 2 Effect of Total Lipid to Polysorbate 80 Ratio (2:1 and 3:1) on Particle Size, Polydispersity Index, and Zeta Potential of NLC Placebos, Composed of Glyceryl Distearate and Oleic Acid (Mean ± SD, n = 3)

Formulation Composition (%w/v)	P4	P9
Glyceryldistearate	3.0	4.5
Oleic acid	1.0	1.5
Polysorbate 80	2.0	2.0
Poloxamer 188	0.25	0.25
Glycerin	2.25	2.25
Water up to (mL)	10	10
Particle size (nm)	142.3±3.9	226.0±11.2
Polydispersity index	0.38±0.01	0.60±0.05
Zeta potential (mV)	−27.1±1.7	−27.8±0.5

Abbreviation: P, placebo.

Table 3 Effect of Liquid Lipid on Particle Size, Polydispersity Index, Zeta Potential, % Drug Content, and % Entrapment Efficiency (Mean ± SD, n = 3)

Formulation Composition (%w/v)		F1	F2
Ciprofloxacin		0.1	0.1
Natamycin		0.3	0.3
Glyceryldistearate		3.0	3.0
Oleic acid		1.0	–
Castor oil		–	1.0
Polysorbate 80		2.0	2.0
Poloxamer 188		0.25	0.25
Glycerin		2.25	2.25
Water up to (mL)		10	10
Particle size (nm)		196.2±1.2	283.4±4.2
Polydispersity index		0.43±0.06	0.66±0.03
Zeta potential (mV)		−28.1±1.4	−29.1±2.4
Drug content (%)	CIP	102.9±3.0	98.9±2.6
	NT	100.9±2.8	98.7±4.3
Entrapment efficiency (%)	CIP	80.9±2.9	19.2±2.2
	NT	98.7±1.9	95.5±2.5

Figure 1 (A) particle size (PS), (B) polydispersity index (PDI), (C) zeta potential (ZP), (D) drug content of ciprofloxacin and natamycin, and (E) entrapment efficiency (EE) of ciprofloxacin and natamycin for F1 formulation over three months storage at 4°C and 25°C (mean ± SD, n = 3).

Table 4 The Viscosity of F1 and F1-IG Formulations with Different Gellan Gum Concentrations (mean±SD, n = 3)

Formulation	Gellan Gum (% w/v)	GT	GRT (h)	η without STF (cP)	η with STF (cP)
F1	0.0	NA	NA	4.9±0.1	5.1±0.1
F1-IG2	0.2	Immediate	>24	11.2±0.2	22.3±0.1
F1-IG3	0.3	Immediate	>24	75.9±2.8	308.4±4.4
F1-IG4	0.4	Immediate	>24	128.0±6.7	800.0±10.2

Abbreviations: GT, gelation time; GRT, gel residence time.

Figure 2 Viscosity of F1-IG2 formulation in the presence and absence of STF following one-month storage at 25°C (mean ± SD, n = 3).

Figure 3 FTIR spectra of (A) ciprofloxacin, (B) natamycin, (C) oleic acid, (D) Glyceryl distearate, (E) physical mixture (ciprofloxacin, natamycin, oleic acid and glyceryl distearate), (F) placebo NLC (P4), and (G) NLC formulation (F1).

Figure 4 Transmission electron micrographs of F1 (A) and F1-IG2 (B) formulations.

Figure 5 In vitro release of ciprofloxacin and natamycin from F1, F1-IG2, NT-C, and CIP-HCL-C formulations through thermo scientific™ slide-A-lyzer™ MINI dialysis device (10K MWCO) (mean ± SD, n = 3).

Table 5 Mathematical Model Fitting of Release Kinetics of Ciprofloxacin and Natamycin from F1 and F1-IG2 Formulations (Mean ± SD, n = 3)

Equation	Q0-Q = kt	ln Q = kt	Q0-Q = kt^1/2	log (Q0-Q) = nlogt + logk
Coefficient of determination (R^2)
Formulation	Zero-order	First-order	Higuchi	Korsmeyer-Peppas
				R^2	n
CIP
F1	0.8756	0.9561	0.9908	0.9989	0.54
F1-IG2	0.8935	0.9566	0.9795	0.9897	0.57
NT
F1	0.9897	0.9796	0.9043	0.9911	0.83
F1-IG2	0.9887	0.9828	0.8340	0.9977	1.2

Notes: Where, Q_o and Q represent initial drug content at the time t_o and drug content at time t, respectively; Zero-order model: % drug released vs time; First order model: amount drug remaining vs time; Higuchi model: % drug released vs square root of time; Korsmeyer–Peppas model: log % drug released vs log time.

Figure 6 Transcorneal flux and permeability of ciprofloxacin and natamycin from F1, F1-IG2, NT-C, and CIP-HCl-C formulations through the isolated rabbit cornea (mean ± SD, n = 3, *; means significant difference compared to control formulation).