Self-Nano-Emulsifying Drug-Delivery Systems: From the Development to the Current Applications and Challenges in Oral Drug Delivery

Approximately one third of newly discovered drug molecules show insufficient water solubility and therefore low oral bio-availability. Self-nano-emulsifying drug-delivery systems (SNEDDSs) are one of the emerging strategies developed to tackle the issues associated with their oral delivery. SNEDDSs are composed of an oil phase, surfactant, and cosurfactant or cosolvent. SNEDDSs characteristics, their ability to dissolve a drug, and in vivo considerations are determinant factors in the choice of SNEDDSs excipients.

A SNEDDS formulation can be optimized through phase diagram approach or statistical design of experiments. The characterization of SNEDDSs includes multiple orthogonal methods required to fully control SNEDDS manufacture, stability, and biological fate. Encapsulating a drug in SNEDDSs can lead to increased solubilization, stability in the gastro-intestinal tract, and absorption, resulting in enhanced bio-availability. The transformation of liquid SNEDDSs into solid dosage forms has been shown to increase the stability and patient compliance.

Supersaturated, mucus-permeating, and targeted SNEDDSs can be developed to increase efficacy and patient compliance. Self-emulsification approach has been successful in oral drug delivery. The present review gives an insight of SNEDDSs for the oral administration of both lipophilic and hydrophilic compounds from the experimental bench to marketed products.

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Materials (Table 1: Commonly used oils, surfactants, and cosolvents)

General Class	Example	Commercial Name	Acceptability
OILS
Medium-chain	Triglycerides of capric/caprylic acids	Captex® 300, 350, Labrafac® CC, Crodamol GTCC	P/O/T/Oc/M
	Di-glycerides of capric/caprylic acids	Capmul® MCM, Akoline® MCM	O/T
	Monoglycerides of capric/caprylic acids	Capryol® 90, Capryol® PGMC, Imwitor® 742	O/T
Long-chain	Glyceryl monooleate	Peceol®, Capmul®-GMO	O/T
	Glyceryl monolinoleate	Maisine®-35	O/T
Propylene glycol fatty acid esters	Propylene glycol monocaprylate	Capmul® PG-8, Sefsol 218	O/T
	Propylene glycol dicaprylate/caprate	Miglyol® 840, Captex® 200	O/T
	Propylene glycol Monolaurate	Lauroglycol® 90, Capmul® PG-12, Lauroglycol® FCC	O/T
SURFACTANTS
Polysorbates	Polysorbate esters	Tween® 20, Tween® 80	P/O/T/Oc M
Sorban esters	Sorban esters	Span® 20,80, Crill® 4	P/O/T/Oc M
Castor oil esters	Ethoxylated castor oil	Cremophor®-EL, Etocas® 35 HV	O/T
	Hydrogenated castor oil	Cremophor® RH40, 60, Croduret® 40	O/T
Polyglycolyzed glycerides	Linoleoyl/Oleoyl Macrogol glycerides	Labrafil® 1944, 2121 CS	O/T
	Caprylocaproyl macrogol glycerides	Labrasol®	O/T
COSOLVENTS
Alcohols	Short chain Alcohols	Ethanol, benzyl alcohol	P/T/Oc/M
	Alkane diols	Propylene glycol	P/T/Oc/M
Polyethylene glycols	Polyethylene glycols	PEG 400, 600	P/T/Oc/M
Esters	Glycerol esters	Transcutol®	O/T

Article information: Buya, A.B.; Beloqui, A.; Memvanga, P.B.; Préat, V. Self-Nano-Emulsifying Drug-Delivery Systems: From the Development to the Current Applications and Challenges in Oral Drug Delivery. Pharmaceutics 2020, 12, 1194. https://doi.org/10.3390/pharmaceutics12121194