Dipalmitoyl-phosphatidylglycerol DPPG

With respect to safety and the use of phospholipids, no NDA-supporting chronic inhalation studies have been conducted except for those found in commercial pulmonary surfactants. These studies presumably will have involved intratracheal instillation and not aerosolization, since the primary indication is respiratory distress syndrome of the newborn. Nevertheless, the fact that these products are available suggests that synthetic versions of natural lipids such as dipalmitoyl phosphatidylcholine (DPPC) and dipalmitoyl phosphatidylglycerol (DPPG) are likely to be well tolerated. This assumption has been supported from subchronic aerosol studies in mice [60] and acute single-dose aerosol studies in man, the latter involving soy-derived phosphatidylcholines [61]. 

DSPC distearoyl phosphatidylcholine DPPG dipalmitoyl phosphatidylglycerol MI mechanical index... 

Figure 1.90 Dipalmitoyl L-oc-phosphatidylglycerol (DPPG) layer to illustrate crystal packing in 2D-lamellar layers. In lipid assembly terms this can be considered secondary/tertiary structure formation.

Fig. 2.7. Phase transition temperatures of dimyristoyl (DMPG) and dipalmitoyl (DPPG) phosphatidylglycerol as a function of the bulk NaCl concentration, c, and the headgroup ionization. PG° 0.1 N HCl pH 1.08 PG triethanolamine -HCl/NaOH pH 7.0 (Cevc et al., 1980).

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