Stability and antimicrobial effect of amikacin-loaded solid lipid nanoparticles

Figures & data

Figure 1 Design of serial dilution susceptibility testing method.

Figure 2 Release profiles of amikacin from SLNs at three different storage temperatures A) before and B) after freeze drying.

Table 1 MBC and MIC of free amikacin and SLNs of amikacin before and after freeze drying with respect to Pseudomonas aeruginosa

Type of antibacterial activity	Free amikacin (μg/mL)	Amikacin-SLNs (μg/mL)
		After freeze drying	Before freeze drying
MBC	4	8	8
MIC	8	16	16

Abbreviations: MBC, minimum bacteriostatic concentration; MIC, minimum inhibitory concentrations; SLN, solid lipid nanoparticles.

Figure 3 Photographs of the zone of inhibition produced by free amikacin and its SLNs in A) primary dispersion of SLNs and B) after freeze drying and re-dispersion of SLNs.

Figure 4 SEM photographs of SLNs of amikacin stored 60 days at A) 4°C, B) 25°C, C) 40°C, and D) lyophilized SLNs stored at 40°C.

Table 2 Results of stability study on SLNs of amikacin before and after freeze drying

SLNs form	Temp (°C)	Mean particle size (nm)							Mean zeta potential (mV)							Mean PDI
		Time (day)							Time (day)							Time (day)
		1	3	7	15	30	45	60	1	3	7	15	30	45	60	1	3	7	15	30	45	60
Primary dispersion of sLNs	4	150	269	309	372	430	540	690	+4	+3	0	+1	0	−2	−1	0.46	0.43	0.050	0.54	0.7	0.9	1.0
	25	150	350	400	560	590	750	980	+4	+1	0	0	−2	0	0	0.46	0.50	0.60	0.87	0.98	1.0	1.2
	40	150	400	450	538	678	856	996	+4	0	0	+1	0	+1	0	0.46	0.60	0.77	0.89	0.90	1.0	1.0
Freeze-dried sLNs	4	190	193	192	195	198	200	199	+13	+15	+14	+15	+15	+14	+13	0.35	0.43	0.40	0.35	0.45	0.48	0.39
	25	190	194	195	195	196	198	197	+13	+17	+18	+14	+16	+17	+18	0.36	0.43	0.39	0.49	0.43	0.50	0.49
	40	190	198	185	210	196	199	194	+13	+16	+15	+15	+13	+16	+15	0.36	0.45	0.37	0.46	0.43	0.55	0.41