Noveon AA-1 (Goodrich).
Polycarbophils are synthetic, high-molecular-weight, crosslinked
polymers of acrylic acid. These poly(acrylic acid) polymers are
crosslinked with divinyl glycol. They are synthesized via precipitation
polymerization in ethyl acetate and then dried.
GRAS listed. Included in the FDA Inactive Ingredients Database
(buccal (tablet) and ophthalmic (solution) preparations; topical
patches; vaginal gel). Included in nonparenteral medicines licensed
in the UK.
Polycarbophil polymers are stable, hygroscopic materials. They do
not undergo hydrolysis or oxidation under normal conditions. Heat
aging at temperatures below 104°C for up to 2 hours does not affect
the efficiency of the dry polymer. However, prolonged exposure to
excessive temperatures can result in discoloration, reduced stability,
and in some cases plasticization of the polymer. Complete
decomposition occurs with heating for 30 minutes at 260°C.
Polycarbophil polymers do not support bacteria, mold, or fungal
growth in dry powder form. Microbial growth may occur in
mucilages of the polymer solution. Although the gel properties are
not affected by such growth, this phenomenon is usually
unacceptable. The addition of appropriate preservatives prevents
mold and bacterial growth in these mucilages. Mucilages and
emulsions containing these polymers are stable under freeze–thaw
conditions but exposure to high temperatures results in a drop in
Polycarbophil polymers are very hygroscopic and should be
packed in airtight, corrosion-resistant containers. They should be
stored in a cool, dry place, and the container should be kept closed
when not in use. Moisture pickup does not affect the efficiency of
the resins, but resin containing high levels of moisture is more
difficult to disperse and weigh accurately. Glass, plastic, or resinlined
containers are recommended for products containing polycarbophil.
Packaging in aluminum tubes usually requires formulations
to have a pH less than 6.5, and packaging in other metallic
tubes or containers necessitates a pH greater than 7.7 to prolong
Polycarbophil polymers have a long history of safe and effective use
in topical gels, creams, lotions, and ointments. They have been
shown to have extremely low irritancy properties and are
nonsensitizing with repeated usage.
The use of these polymers is supported by extensive toxicological
(guinea pig, oral): 2.0 g/kg
(mouse, IP): 0.039 g/kg
(mouse, IV): 0.070 g/kg
(mouse, oral): 4.6 g/kg
(rat, oral): >2.5 g/kg
(rabbit, skin): >3.0 g/kg
Chronic oral toxicity No significant effects in rats or dogs were
observed after being fed with resin as 5% of the diet for 6?
Polycarbophil occurs as fluffy, white to off-white, mildly acidic
polymer powder with slightly acetic odor.
Conventionally, polycarbophil is used as a thickening agent at very
low concentrations (less than 1%) to produce a wide range of
viscosities and flow properties in topical lotions, creams, and gels, in
oral suspensions, and in transdermal gel reservoirs. It is also used as
an emulsifying agent in topical oil-in-water systems.
Polycarbophil is an excellent bioadhesive in buccal, ophthalmic,
intestinal, nasal, vaginal, and rectal applications. Buccal tablets
prepared using polycarbophil have shown high bioadhesive force
and prolonged residence time, and proved to be nonirritative in in
vivo trials with human buccal mucosa.Polycarbophil has been
used in combination with hydroxypropyl methylcellulose to
develop a bilayered buccal bioadhesive film formulation of nicotine
hydrogen tartrate for smoking cessation therapy.It is also useful
in designing controlled-release formulations and for drugs that
undergo first-pass metabolism.Polycarbophil buccoadhesive
disks have also been developed in formulations increasing the
bioavailability and transmucosal absorption of poorly watersoluble
drugs.Sublingual tablets of buprenorphine formulated
using polycarbophil have shown superior mucoadhesive strength
when compared to those using carbomer.
Polycarbophil gels have been used for delivering bioactive
substances for local application to gingival,oropharyngeal
and periodontal areas, and also for ocular drug delivery.
The nasal retention of plasmid DNA is highly prolonged with the
use of polycarbophil as the gelling agent. Polycarbophil has also
been used to design an insulin liquid suppository for rectal
application.A vaginal gel of econazole has shown improved
therapeutic benefit on topical application in vaginal candidiasis.
An intravaginal administration of polycarbophil gel alone and with
carbomer is associated with improved signs of bacterial vaginosis.
Polycarbophil with carboxymethylcellulose sodium are the
polymers of choice for the formulation of an acid-buffering
bioadhesive vaginal tablet of clotrimazole and metronidazole.
Mucoadhesive vaginal vaccine delivery systems using polycarbophil
have proved to be effective in the induction of mucosal and systemic
immune responses.Polycarbophil gels have been used to deliver
granulocyte-macrophage colony-stimulating factor (GM-CSF)
effectively to genital preneoplastic lesions.Polycarbophil microspheres
have been formulated for drug delivery to oral and
nasal cavities. Floating-bioadhesive microspheres coated with
polycarbophil have been found to be a useful gastroretentive drug
delivery system for the treatment of Helicobacter pylori.
Conjugation with L-cysteine (thiolated polycarbophil) greatly
enhances the mucoadhesive properties of polycarbophil and
can be used as a platform for oral and nasal polypeptide
delivery (e.g. heparin, human growth hormone,insulin,antigens for oral protein vaccination and for ocular
and transdermal drug delivery systems.These compounds have
shown higher stability and more controlled drug release. They have
also been reported to act as a permeation enhancer by triggering the
reversible opening of the tight junctions between the cells, thereby
allowing the paracellular transport of peptides, in addition to
locally deactivating the most important enzymes of the gastrointestinal
tract.Due to its likelihood for inhibiting Pglycoprotein,
thiolated polycarbophil has demonstrated improved
bioavailability of an oral paclitaxel formulation.
Heat may be generated if polycarbophil comes into contact with
strong basic materials such as ammonia, sodium hydroxide,
potassium hydroxide, or strongly basic amines. Polycarbophil
polymers are not compatible with cationic polymers, strong acids,
and high levels of electrolytes, as electrolytes tend to reduce the
viscosity of polycarbophil-based gels.