Purpose: Self-nanoemulsifying Drug Delivery Systems (SNEDDS) can be employed to improve the absorption of both hydrophobic and hydrophilic drugs. Surfactants and mixed glycerides (a combination of tri- and mono/diglycerides) are two common groups of excipients in SNEDDS formulation. Capmul MCM (C8/10 mono/diglycerides) is commonly used in SNEDDS. Since Capmul MCM has an HLB value of 5.0-6.0, it can act as a co-surfactant as well. However, the possible toxic effects of mixed glycerides containing Capmul MCM has not been thoroughly investigated. Hence, the purpose of this study is to explore the in vitro cytotoxicity of Capmul MCM by itself alone as well as in SNEDDS formulation and its impact on the transport of the nanoemulsions droplets through the cell monolayers.
Methods: Soybean oil (C18 triglycerides), Captex8000 (C8 triglycerides), Capmul MCM (C8 and C10 glycerides containing 60% monoglycerides and 35% diglycerides) were used. Two lipid compositions, Soybean oil-Capmul MCM (7:3) and Captex8000-Capmul MCM (1:1), were mixed separately with Cremophor RH40 in 1:1 weight ratio to prepare SN-1 and SN-2 preconcentrates, respectively. The third preconcentrate (SN-3) was prepared by mixing Captex8000 and Cremophor RH40 in 1:4 weight ratio. These preconcentrates were loaded with a trace amount of 14C-Triolein, and then diluted with Dulbecco’s Modified Eagle Medium (DMEM) to form nanoemulsions at various concentrations. The cytotoxicity on MDCK cells by Capmul MCM alone and the nanoemulsions were studied by MTT assay. The transport of the nanoemulsions through MDCK monolayers in Transwell inserts were investigated for two hours. The monolayers which TEER was significantly reduced during the 2-hr transport experiment were then further cultured in fresh culture media for four hours after the nanoemulsions being removed. After that, the transport markers (14C-Mannitol and 3H-Propranolol) were added to the donor side and the permeation of the markers through the monolayers were studied for two hours. TEER was measured every hour during the whole study.
Results: The droplet sizes of SN-1 (2%), SN-2 (2%), and SN-3 (5%) were 168.7 ± 56.6, 29.9 ± 4.7, and 27.0 ± 7.4 nm, respectively. Capmul MCM (0.3%-1.0% in DMEM) caused 80% or more reduction in cell viability. Similar effect was observed from the nanoemulsions (2-3% SN-1 and 2% SN-2, containing 0.3%-0.6% of Capmul MCM). However, the nanoemulsions of 5-10% SN-3 (without Capmul MCM) caused only about 30% reduction of cell viability. The transport of 14C-Triolein and lipid droplets across the monolayers were found only in 2% SN-2 (containing 0.5% Capmul MCM), but not in other nanoemulsions. There was a 40%-60% reduction of TEER after the 2-hr exposure to 1-3% SN-1 and 1-2% SN-2, while there was no change of TEER when exposure to 5-10% SN-3. After the 6-hr recovery experiment, all the reduced TEER came back close to the initial value except those exposed to 2% SN-2. The transport of both 14C-mannitol and 3H-propranolol were highest through the monolayers previously exposed to 2% SN-2.
Conclusion: Capmul MCM could cause significant but possibly reversible toxicity to MDCK cell monolayers at 0.3% or higher concentrations, regardless by itself alone or in nanoemulsions. The lipid droplets of approximately 30 nm could transport across the MDCK monolayers when its integrity compromised by Capmul MCM.
Kanyaphat Bunchongprasert
– Ph.D. Candidate, St. John's University, Jamaica, New YorkKanyaphat Bunchongprasert
– Ph.D. Candidate, St. John's University, Jamaica, New YorkKanyaphat Bunchongprasert
– Ph.D. Candidate, St. John's University, Jamaica, New York๋Jun Shao
– Associate Professor, St. John's University, Queens, New YorkKanyaphat Bunchongprasert
– Ph.D. Candidate, St. John's University, Jamaica, New York217 Views