Lutrol® L and
Supersedes issue dated February 2010
03_100102e-03/Page 1 of 8
Poloxamers Ph. Eur., Poloxamer USP/NF
Poloxamers for Pharmaceutical Use
The Lutrol L and F-block copolymers are synthetic copolymers of ethylene oxide
and propylene oxide represented by the following chemical structure:
Wherein a and b blocks have the following values:
Lutrol L 44 is a milky white paste or liquid. The product contains d,l-alpha toco-
The Lutrol F-grades are white, coarse-grained powders with a waxy consistency.
They contain an appropriate quantity of the antioxidant BHT.
See separate document: “Standard Specification (not for regulatory purposes)“
available via BASF’s WorldAccount: https://worldaccount.basf.com (registered
US Drug Master File
BASF maintains a Drug Master File for Poloxamers at the FDA and is familiar with
supplying information to the FDA to assist customers in obtaining FDA authorizations.
Further Typical Properties
Solid, prill Solid, prill Solid, prill Solid, prill
50 max. 100 max. 100 max. 80 max. 120 max.
50 – 125 50 – 125 50 – 125 50 – 125
>100 °C >100 °C >100 °C >100 °C
The poloxamers are not only readily soluble in water but also in polar and non-
The average particle size of the prilled Lutrol F-grades is around 1000 µm.
Apart from the prilled products some microprilled poloxamers were developed
for specific formulation needs. The microprilled products Lµtrol micro 68 (micro-
prilled Poloxamer 188) and Lµtrol micro 127 (microprilled poloxamer 407) were
microprilled to an average particle size of approximately 50 µm. Both products
For further information on the micropril ed Lµtrol grades please refer to the
individual Technical Information sheets.
Product Properties and
When dispersed in the liquid at low concentrations, Poloxamers exist individual y as
fields of application
monomolecular micel es. When the concentration of the poloxamers in the system
increases, this results in the formation of multimolecular aggregates. Polypropylene
oxide (PPO) usual y forms central hydrophobic cores wherein methyl groups interact
via Van der Waals forces with the substance undergoing solubilization. However,
water solubility is believed to be due to the polyethylene oxide (PEO) block by
hydrogen bonding interactions of ether oxygen with water molecules. Due to these
interactions, poloxamers are readily soluble in polar and non-polar organic solvents
which al ows a wide range of dosage forms to be formulated with these Excipients.
Lutrol L 44 is the only monographed poloxamer that is liquid at room temperature.
It is applied for liquid filled soft gel capsules as a dispersion medium for APIs.
Lutrol F 68 and Lutrol F 87 are used as wetting agents, as emulsifiers and
solubilizers, Lutrol F 68 has been formulated in liquid dosage forms for parenteral
use. Lutrol F 68 and Lutrol F 87 are suitable to prepare solid dispersions and to
improve the solubility, absorption and bioavailability of low-solubility actives in
solid oral dosage forms. The corresponding dosage forms are usual y processed
by melting or granulation. In addition, Lutrol F 68 can also act as a co-emulsifier
Aqueous solutions of Lutrol F 68 have Newtonian flow properties that change to
non-Newtonian behavior at higher concentrations. Aqueous solutions containing
more than 20% Lutrol F 68 are thermoreversible, i.e. the minimum viscosity is
between 15 and 60 °C and the maximum viscosity between 75 and 80 °C (see
Repeated heating and cooling does not affect this property.
The gelling properties of individual poloxamers depend on their molecular
weight. Those with higher molecular weights show a pronounced gelling effect
at lower concentrations. Thus Lutrol F 108 and Lutrol F 127 are the preferred
poloxamers for gels. At lower concentrations, the poloxamers can be used to
modulate the viscosity of liquid formulations.
Fig. 1: Dynamic viscosity of aqueous solutions of Lutrol F 68 as a function of
temperature using a HAAKE Rheostress 6000 (RS) with a plate/plate configuration
PP60Ti with 1,0mm distance and an amplitude of 0.010rad and a frequency of
Lutrol F 108 and Lutrol F 127 are used primarily as thickening agents and gel
formers, but also as co-emulsifiers and consistency enhancers in creams and
liquid emulsions. Lutrol F 127 is also used as a solubilizer for certain active sub-
stances such as nifedipine, naproxen and fenticonazole as well as for essential
oils in pharmaceutical formulations.
Moreover, Lutrol F 127 is suitable for the formulation of active substances that show
reduced solubility as well as chemical stability as a result of neutralization of gel
formulations. Owing to its ability to affect viscosity, Lutrol F 108 and Lutrol F 127
are suitable as stabilizers for topically administered suspensions. Lutrol F 127 is
also used in toothpastes, gargles and mouthwashes.
In solid oral dosage forms the microprilled products Lµtrol micro 68 and Lµtrol
micro 127 are successfully formulated because the very coarse prilled products
are not very suitable as content uniformity of the solid oral dosage form will be
Lutrol F 108 and Lutrol F 127 show the characteristic property of thermoreversible
gelation. The reversible thermal behavior of these two poloxamers in case of dilute
as well as concentrated solutions was studied extensively. Generally, this type of
behavior is observed in aqueous solutions of concentration range 16 – 30% w/w.
They are liquid when refrigerated (4 – 5 °C) or heated to temperatures exceeding
70 °C but turn into gel form when at room temperature. They exhibit maximum
viscosity in the range of 30 – 60 °C.
The gels thus formed are reversible again on cooling or heating.
Preparation of gels
Gels may generally be prepared by two methods:
Lutrol F 108 or Lutrol F 127 are completely dissolved in water at room temperature
or water pre-cooled to approx. 5 °C. Active substances that are insoluble in water
are dissolved in ethanol, isopropanol or propylene glycol and mixed with the
aqueous phase containing the poloxamer at 5 °C to form a homogeneous mass.
Lutrol F 127 is dissolved in water at approx. 70 °C. Active substances that are
insoluble in water are dissolved in ethanol, isopropanol or propylene glycol at
70 °C and mixed with the warm aqueous phase to form a homogeneous mass.
The gel forms when the solution cools to room temperature.
Both methods of preparation will generally yield gels with comparable properties.
Adding Lutrol F 108 or Lutrol F 127 to the hot aqueous phase to fast the formation
of lumps may happen. These wil only dissolve after standing for several hours. Any
loss of solvent must be replaced, otherwise a thixotropic ef ect may be observed.
The “cold process” for the preparation of gels, particularly if active substances
sensitive to heat are formulated is highly recommended. In order to prevent the
gel to entrap air bubbles, a vacuum should be applied to the formulation before
Gels using identical concentrations of Lutrol F 127 but being prepared by either
of the two methods described above did not reveal differences in their viscosity
Fig. 2: Viscosity of aqueous Lutrol F 127 prepared either by the hot (orange curve)
or cold (black curve) process. Viscosity determination using a HAAKE Rotovisco
1 rotational viscometer with a double gap concentric cylinder measuring geometry
The following figure shows the influence of increasing concentrations of Lutrol F
127 on sol-gel transition temperature and on the gel strength. The determination
is performed using an oscil ating plate/plate configuration to avoid detrimental
effects of higher shear rates on the gel strength.
Fig. 3: Complex dynamic viscosity of aqueous Lutrol F 127-gels as a function of
temperature. Viscosity determation was performed using a HAAKE Rheostress
6000 with a plate/plate configuration PP60Ti with an amplitude of 0.010 and a
Figure 4 shows the influence of the shear rate on the viscosity of a gel formulated
with 20% Lutrol F 127. The dynamic viscosity was determined using a HAAKE
Rotovisco 1 (RV) with a double gap concentric cylinder measuring geometry DG43
with a cup. For the complex dynamic viscosity a HAAKE Rheostress 6000 (RS)
with a plate/plate configuration PP60Ti with 1.0 mm distance and an amplitude
of 0.010 rad and a frequency of 1000/s was applied
Fig. 4: Influence of the shear rate on the gel strength of a 20% Lutrol F 127-gel
The dynamic viscosity of Lutrol F 108 and Lutrol F 127 gels may be affected by
the addition of electrolytes, moisturizers, alcohols and surfactants. Figure 5 demon-
strate the influence of sodium chloride and potassium chloride in a 20% Lutrol F
127-gel. The addition of electrolytes at concentrations of around 1% increases
the viscosity with little or no impact on the sol-gel transition temperature. Higher
concentrations demonstrate a reduced gel ing temperature with increased dynamic
viscosity readings. In contrast to this, ethanol increases the gel formation temperature.
The use of anionic surfactants may inhibit gel formation, even at Lutrol F 127 con-
centrations exceeding 20%. This is true, for example, for sodium lauryl sulphate
at concentrations above 2%. Low pH values affect both the sol-gel transition
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85
Fig. 5: Pour point of 25% aqueous Lutrol F 127 gels at different NaCl – or KCl –
Examples for Gel Formulations
Topically applied gels formulated with Lutrol F 108 and Lutrol F 127 feel tacky to
a certain extent. This tackiness can be minimized when the gels are formulated
with 1% to 2% of either propylene carbonate or isopropyl myristate.
Lutrol F 127 gel
Description: clear, stable, colorless gel.
Lutrol F 108 gel
Description: clear, stable, colorless gel.
Lutrol F 127/F 68 gel
Description: clear, stable, colorless gel
Article numbers & Packaging
50143751 55116438 56494120 50149504 55097782
54779199 51633115 50102804 50118158 51632903
Stability and storage
The retest period for the Lutrol L and Lutrol F-grades is two years when stored in
properly sealed containers at temperatures below 25 °C.
Handling and Disposal
Please refer to the individual Material Safety Data Sheet (MSDS) for instructions
on safe and proper handling and disposal.
For proper product handling and sampling homogenization of the drum content
is necessary (thoroughly mixing at room temperature).
This document, or any answers or information provided herein by BASF, does not
constitute a legal y binding obligation of BASF. While the descriptions, designs, data
and information contained herein are presented in good faith and believed to be
accurate, it is provided for your guidance only. Because many factors may affect
processing or application/use, we recommend that you make tests to determine
the suitability of a product for your particular purpose prior to use. It does not relieve
our customers from the obligation to perform a ful inspection of the products upon
delivery or any other obligation. NO WARRANTIES OF ANY KIND, EITHER EXPRESS
OR IMPLIED, INCLUDING WARRANTIES OF MERCHANTABILITY OR FITNESS
FOR A PARTICULAR PURPOSE, ARE MADE REGARDING PRODUCTS DESCRIBED
OR DESIGNS, DATA OR INFORMATION SET FORTH, OR THAT THE PRODUCTS,
DESIGNS, DATA OR INFORMATION MAY BE USED WITHOUT INFRINGING THE
INTELLECTUAL PROPERTY RIGHTS OF OTHERS. IN NO CASE SHALL THE
DESCRIPTIONS, INFORMATION, DATA OR DESIGNS PROVIDED BE CONSIDERED
A PART OF OUR TERMS AND CONDITIONS OF SALE.
- Care Chemicals Division - Pharma Ingredients & Services - 67117 Limburgerhof - www.pharma-ingredients.basf.com
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