Tretinoin-loaded liposomal formulations: from lab to comparative clinical study in acne patients

Figures & data

Table 1. Experimental plan of the 2⁴ factorial design for the preparation of tretinoin liposomes.

Variables	Levels
Cholesterol (Ch.)	Present	Absent
Drug concentration (g %)	0.01	0.025
Charge inducer (DCP)^a	Present	Absent
Method of preparation	Ether injection method	Hydration method

^aDcp: dicetylphosphate.

Table 2. Composition of the prepared tretinoin liposomes.

Formulation code	Phospholipid amount (mg)	Method of preparation	Tretinoin concentration (mg%)	Negative charge inducer (DCP)^a	Cholesterol^b
Formula 1	900 mg	Ether injection method	0.01	Present	Absent
Formula 2			0.01	Present	Present
Formula 3			0.01	Absent	Absent
Formula 4			0.01	Absent	Present
Formula 5			0.025	Present	Present
Formula 6			0.025	Absent	Present
Formula 7			0.025	Absent	Absent
Formula 8			0.025	Present	Absent
Formula 9		Film hydration method	0.01	Present	Absent
Formula 10			0.01	Present	Present
Formula 11			0.01	Absent	Absent
Formula 12			0.01	Absent	Present
Formula 13			0.025	Present	Present
Formula 14			0.025	Absent	Present
Formula 15			0.025	Absent	Absent
Formula 16			0.025	Present	Absent

^aTen milligrams DCP was added.

^bOne hundred milligrams cholesterol was added.

Figure 1. TEM of F13.

Table 3. Physicochemical characterization of different tretinoin liposomal dispersions.

	Mean volume distribution (μm ± SD)			Mean vesicle size (µm)	PI	Incorporation efficiency
Formulation code	d10%	d50%	d90%	Mean ± SD		Mean ± SD (%)
F1	0.31	0.35	0.5	0.407 ± (0.045)	0.542	38.2 ± (3.39)
F2	0.28	0.335	0.49	0.3425 ± (0.024)	0.597	68.6 ± (0.989)
F3	0.32	0.37	0.56	0.407 ± (0.0318)	0.64	44.0 ± (2.19)
F4	0.33	0.38	0.57	0.4125 ± (0.081)	0.63	70.5 ± (2.29)
F5	0.29	0.38	0.49	0.4425 ± (0.053)	0.535	61.2 ± (2.72)
F6	0.29	0.38	0.52	0.4265 ± (0.0372)	0.6	63.0 ± (4.45)
F7	0.35	0.43	0.6	0.4855 ± (0.022)	0.58	45 ± (3.04)
F8	0.366	0.388	0.58	0.474 ± (0.018)	0.551	65 ± (0.81)
F9	0.366	0.408	0.59	0.439 ± (0.001)	0.54	51.3 ± (3.04)
F10	0.35	0.388	0.60	0.38 ± (0.042)	0.64	61.15 ± (3.92)
F11	0.31	0.36	0.52	0.39 ± (0.042)	0.58	65.6 ± (4.49)
F12	0.28	0.417	0.56	0.3985 ± (0.04)	0.67	55.0 ± (4.49)
F13	0.232	0.3	0.41	0.318 ± (0.003)	0.434	73.4 ± (3.81)
F14	0.235	0.305	0.41	0.331 ± (0.014)	0.599	61.85 ± (1.87)
F15	0.34	0.41	0.52	0.409 ± (0.030)	0.439	66.4 ± (1.13)
F16	0.28	0.37	0.47	0.372 ± (0.008)	0.567	68.3 ± (2.33)

Figure 2. Release of tretinoin from liposome formulations prepared by (a) ether injection method and (b) film hydration method after 5 h (N = 3).

Figure 3. DSC thermograms of tretinoin, l-alphalicithin, cholesterol, blank liposomes and tretinoin-loaded liposomes F13.

Table 4. Skin irritation test of tretinoin in different formulations.

Formulation code	Reaction in volunteers (mean ± SD) (N = 10)
Free TRT gel	1.8 ± 0.67
F13 gel	0.2 ± 0.42
Marketed product	1.4 ± 0.31

Figure 4. Comparison of the effect of marketed product and F13 on acne lesions (N = 12).

Table 5. Effect of the two tested formulae (commercial versus F13) on different types of lesions (comedons and papules) during 4 weeks study period (mean ± SE).

Type of lesion	After 1 week		After 2 weeks		After 3 weeks		After 4 weeks
Average improvement % (SE)	Marketed product	F13 formula	Marketed product	F13 formula	Marketed product	F13 formula	Marketed product	F13 formula
Closed comedons	24.13 ± (1.08)	44.65 ± (1.92)	44.57 ± (1.83)	63.07 ± (2.5)	55.32 ± (2.25)	68.03 ± (3.083)	92.14 ± (0.583)	93.24 ± (0.42)
Open comedons	18.72 ± (1.42)	35.15 ± (3.92)	32.76 ± (1.92)	57.47 ± (3.25)	40.96 ± (1.75)	66.71 ± (2.91)	85.30 ± (0.33)	89.25 ± (0.42)
Papules	19.63 ± (1.33)	12.71 ± (2.083)	38.57 ± (2.00)	55.66 ± (2.66)	63.15 ± (2.33)	68.80 ± (2.83)	98.3 ± (0.75)	98.63 ± (0.583)
Total	20.83 ± (15.19)	30.84 ± (34.08)	38.63 ± (23.67)	58.74 ± (32.07)	53.14 ± (28.01)	67.85 ± (33.82)	93.04 ± (8.57)	93.6 ± (6.73)