Preparation, characterization, and in vivo evaluation of intranasally administered liposomal formulation of donepezil

Figures & data

Figure 1 Chemical structure of donepezil (CAS: 120014-06-4).

Figure 2 SEM micrographs of the prepared liposomes of DNP.

Note: Micrographs at a scale of 200 nm (A) and 100 nm (B).
Abbreviations: SEM, scanning electron microscopy; DNP, donepezil.

Figure 3 In vitro release of DNP from liposomes (mean ± standard deviation, n=3).

Abbreviation: DNP, donepezil.

Table 1 Encapsulation efficiency and vesicle size of the prepared liposomes during storage at 4°C and 25°C over a period of 3 months

Time	Particle size (nm)	Encapsulation efficiency (%)	Discoloration/sediment/aggregation
4°C
1 week	103.5±3.7	84.1±5.0	NF
2 weeks	104.1±5.9	83.6±5.3	NF
25°C
1 month	106.8±5.5	82.5±6.2	NF
2 months	109.6±6.6	81.5±4.5	NF
3 months	111.3±8.9	79.3±5.4	NF

Abbreviation: NF, not found.

Table 2 Pharmacokinetic parameters of DNP in plasma post various routes of administration (mean ± SD, n=6)

Pharmacokinetic parameters	Free drug (oral)		Free drug (intranasal)		Liposomes (intranasal)
	Mean	±SD	Mean	±SD	Mean	±SD
Cmax (ng/mL)	55.27	4.97	88.78*	3.50	139.25#	11.41
AUC0–t (ng*h/mL)	234.17	24.04	351.85	20.87	657.97#	65.96
AUC0–∞ (ng*h/mL)	341.41	60.75	475.78	53.53	1,158.13#	194.28
Kel (h^−1)	0.15	0.04	0.17	0.03	0.11	0.03
T1/2 (h)	4.30	1.07	4.18	0.82	5.79	1.49

Notes:

* P<0.05, compared with free drug oral.

# P<0.05, compared with free drug intranasal.

Abbreviations: DNP, donepezil; SD, standard deviation; AUC_0–t, area under concentration–time curve from time zero to time t; AUC_0–∞, area under concentration–time curve from time zero to infinity; T_1/2, terminal elimination half-life; C_max, maximum plasma drug level; K_el, rate of drug removal from the body.

Figure 4 Mean plasma concentration and time profile of donepezil with various routes of administration (mean ± standard deviation, n=6).

Table 3 Pharmacokinetic parameters of DNP in brain post various routes of administration (mean ± SD, n=6)

Pharmacokinetic parameters	Free drug (oral)		Free drug (intranasal)		Liposomes (intranasal)
	Mean	±SD	Mean	±SD	Mean	±SD
Cmax (ng/g)	111.23	8.60	146.91	3.50	214.92*	17.26
AUC0–t (ng*h/g)	575.55	58.26	721.14	40.64	1,003.18*	92.39
AUC0–∞ (ng*h/g)	950.86	159.45	1,170.35	175.04	1,799.37*	220.98
Kel (h^−1)	0.12	0.01	0.13	0.02	0.10	0.02
T1/2 (h)	5.66	0.67	5.55	1.04	6.90	1.14

Note:

* P<0.05, compared with free drug intranasal.

Abbreviations: DNP, donepezil; SD, standard deviation; AUC_0–t, area under concentration–time curve from time zero to time t; AUC_0–∞, area under concentration–time curve from time zero to infinity; T_1/2, terminal elimination half-life; C_max, maximum plasma drug level; K_el, rate of drug removal from the body.

Figure 5 Mean brain concentrations and time profile of donepezil with various routes of administration (mean ± standard deviation, n=6).

Figure 6 Histopathological examinations of heart, lung, kidney, spleen, and liver.

Notes: Sections were processed with hematoxylin and eosin stain for the analysis of level of inflammation and morphology of the tissues. (A) Free donepezil intranasal. (B) Liposomal donepezil intranasal. The scale bars represent 200 µm.

Figure 7 Histopathological examinations of brain and olfactory bulb.

Notes: Sections were processed with hematoxylin and eosin stain for the analysis of level of inflammation and morphology of the tissues. (A) Free donepezil intranasal. (B) Liposomal donepezil intranasal. The scale bars represent 200 µm.

Table 4 Dissolution kinetic parameters for the DNP release from liposomal formulation

Formulation	Correlation coefficients
	Weibull	Higuchi	Zero order	First order
DNP liposomes	0.9861	0.9248	0.7675	0.5631

Abbreviation: DNP, donepezil.