The L
FCS Consortium was established to develop standardized
in vitro tests
for lipid-based
formulations (LBFs) and to examine the utility o
f these tests to probe the
fundamental mechanisms that underlie LBF per
formance. In this publication, the impact o
f bile salt (sodium taurodeoxycholate, NaTDC) concentration and drug loading on the ability o
f a range o
f representative LBFs to generate and sustain drug solubilization and supersaturation du
ring
in vitro digestion testing has been explored and a common d
river o
f the potential
for drug precipitation identi
fied. Danazol was used as a model poorly water-soluble drug throughout. In general, increasing NaTDC concentrations increased the digestion o
f the most lipophilic LBFs and promoted lipid (and drug) tra
fficking
from poorly dispersed oil phases to the aqueous colloidal phase (AP
DIGEST). High NaTDC concentrations showed some capacity to reduce drug precipitation, although, at NaTDC concentrations 鈮? mM, NaTDC e
ffects on either digestion or drug solubilization were modest. In contrast, increasing drug load had a marked impact on drug solubilization. For LBFs containing long-chain lipids, drug precipitation was limited even at drug loads approaching saturation in the
formulation and concentrations o
f solubilized drug in AP
DIGEST increased with increased drug load. For LBFs containing medium-chain lipids, however, signi
ficant precipitation was evident, especially at higher drug loads. Across all
formulations a remarkably consistent trend emerged such that the likelihood o
f precipitation was almost entirely dependent on the maximum supersaturation ratio (SR
M) attained on initiation o
f digestion. SR
M de
fines the supersaturation 鈥減ressure鈥?in the system and is calculated
from the maximum attainable concentration in the AP
DIGEST (assuming zero precipitation), divided by the solubility o
f the drug in the colloidal phases
formed post digestion. For LBFs where phase separation o
f oil phases did not occur, a threshold value
for SR
M was evident, regardless o
f formulation composition and drug solubilization reduced markedly above SR
M > 2.5. The threshold SR
M may prove to be an e
ffective tool in disc
riminating between LBFs based on per
formance.
Keywords:
f="http://pubs.acs.org/action/doSearch?action=search&searchText=poorly+water%5C-soluble+drug&qsSearchArea=searchText">poorly water-soluble drug; f="http://pubs.acs.org/action/doSearch?action=search&searchText=LFCS+Consortium&qsSearchArea=searchText">LFCS Consortium; f="http://pubs.acs.org/action/doSearch?action=search&searchText=lipid%5C-based+drug+delivery+systems&qsSearchArea=searchText">lipid-based drug delivery systems; f="http://pubs.acs.org/action/doSearch?action=search&searchText=SEDDS&qsSearchArea=searchText">SEDDS; f="http://pubs.acs.org/action/doSearch?action=search&searchText=drug+solubilization&qsSearchArea=searchText">drug solubilization; f="http://pubs.acs.org/action/doSearch?action=search&searchText=in+vitro+digestion+testing&qsSearchArea=searchText">in vitro digestion testing; f="http://pubs.acs.org/action/doSearch?action=search&searchText=solubility&qsSearchArea=searchText">solubility; f="http://pubs.acs.org/action/doSearch?action=search&searchText=bioavailability&qsSearchArea=searchText">bioavailability; f="http://pubs.acs.org/action/doSearch?action=search&searchText=in+vitro+models&qsSearchArea=searchText">in vitro models; f="http://pubs.acs.org/action/doSearch?action=search&searchText=precipitation&qsSearchArea=searchText">precipitation; f="http://pubs.acs.org/action/doSearch?action=search&searchText=supersaturation&qsSearchArea=searchText">supersaturation