Uses
In cosmetic and topical medicinal Preparations where good absorption through the skin is desired. A jellied isopropyl myristate was marketed as Estergel (Merck & Co.) .
Description
Isopropyl myristate is odorless when pure. May be synthesized by
conventional esterification of isopropanol with myristic acid.
Occurrence
Reported found in kumquat peel oil, papaya, starfruit, plum brandy, coriander seed and loquat
Definition
ChEBI: Isopropyl tetradecanoate is a fatty acid ester.
Preparation
By conventional esterification of isopropanol with myristic acid
Production Methods
Isopropyl myristate may be prepared either by the esterification of
myristic acid with propan-2-ol or by the reaction of myristoyl
chloride and propan-2-ol with the aid of a suitable dehydrochlorinating
agent. A high-purity material is also commercially available,
produced by enzymatic esterification at low temperature.
Brand name
Estergel (Merck).
General Description
Isopropyl myristate is an ester of isopropyl alcohol myristic acid. It is mainly used as a solubilizer, emulsifier and emollient in cosmetic and topical medicines. It also finds applications as a flavoring agent in the food industry.
Pharmaceutical secondary standards for application in quality control, provide pharma laboratories and manufacturers with a convenient and cost-effective alternative to the preparation of in-house working standards.
Pharmaceutical Applications
Isopropyl myristate is a nongreasy emollient that is absorbed readily
by the skin. It is used as a component of semisolid bases and as a
solvent for many substances applied topically. Applications in
topical pharmaceutical and cosmetic formulations include bath oils;
make-up; hair and nail care products; creams; lotions; lip products;
shaving products; skin lubricants; deodorants; otic suspensions; and
vaginal creams. For example, isopropyl myristate is a
self-emulsifying component of a proposed cold cream formula,
which is suitable for use as a vehicle for drugs or dermatological
actives; it is also used cosmetically in stable mixtures of water and
glycerol.
Isopropyl myristate is used as a penetration enhancer for
transdermal formulations, and has been used in conjunction with
therapeutic ultrasound and iontophoresis.It has been used in a
water-oil gel prolonged-release emulsion and in various microemulsions.
Such microemulsions may increase bioavailability in topical
and transdermal applications. Isopropyl myristate has also been
used in microspheres, and significantly increased the release of drug
from etoposide-loaded microspheres.
Isopropyl myristate is used in soft adhesives for pressuresensitive
adhesive tapes.
Biochem/physiol Actions
Isopropyl myristate (myristic acid isopropyl ester) is used to change the physicochemical characteristics of microsheres such as poly(lactic-co-glycolic acid) (PLGA) microspheres. Isopropyl myristate is used as a oil phase component in the formulaton of microemulsion systems.
Pharmacology
Isopropyl myristate is used in pharmaceutical preparations because it improves
solubility and increases absorption through the skin. External uses include a non-irritating iodine
preparation for disinfecting the skin (Powers & Rieger, 1963) and aerosol bactericidal preparations
for feminine hygiene use without irritation of the skin and mucous membranes (Geistlich, 1970;
Watson. 1969). Preparations for internal use include oral steroid formulations (Hirata, 1970) and
anaesthetic injection solutions (Davis, Pearce & Connor, 1972).
Veterinary medications containing isopropyl myristate include oral or parenteral compositions
for lungworm infections (N. V. Philips' Gloielampenfabrieken, 1964) and a spray formulation for
bovine udders to treat mastitis, combat infection and improve the general skin condition (Kraus,
1965). Isopropyl myristate has been found to be an effective repository vehicle for im injection
of penicillin in rabbits and for sc administration of oestrogens in ovariectomized rats (Platcow
& Voss, 1954).
In assays on human forearms, vasoconstrictor activity of ointment preparations containing 0025%
betamethasone 17-benzoate in white soft paraffin was increased by the presence of isopropyl myristate
(Pepler, Woodford & Morrison, 1971). Donovan, Ohmart & Stoklosa (1954) noted that the good
solvent properties of isopropyl myristate might increase the therapeutic activity of formulations
by the apparent alteration in particle size of the active ingredients, so that further evaluation and
clinical study would be necessary before its use in extemporaneous compounding could be recommended.
Studies in which the antifungal activity of paraben esters solubilized by surfactants was
decreased by isopropyl myristate (Matsumoto & Aoki, 1962) indicate that the effectiveness of medicinal
substances may be influenced by the presence of surfactants and oily ingredients such as
isopropyl myristate.
Side effects
Thrapecylate myristate is a medicine used to treat head lice infestations in adults and children 4 years of age and older. Common side effects include skin irritation, rash, and contact dermatitis.
Safety
Isopropyl myristate is widely used in cosmetics and topical
pharmaceutical formulations, and is generally regarded as a
nontoxic and nonirritant material.
LD50 (mouse, oral): 49.7 g/kg
LD50 (rabbit, skin): 5 g/kg
Metabolism
Higher molecular weight aliphatic esters are thought to be readily hydrolysed to the corresponding alcohols and acids which are then metabolized; isopropyl myristate is undoubtedly hydrolysed to normal metabolic products (Fassett, 1963). When myristic acid (as the ethyl ester) was fed to dogs,
storage
Isopropyl myristate is resistant to oxidation and hydrolysis, and
does not become rancid. It should be stored in a well-closed
container in a cool, dry place and protected from light.
Incompatibilities
When isopropyl myristate comes into contact with rubber, there is a
drop in viscosity with concomitant swelling and partial dissolution
of the rubber; contact with plastics, e.g. nylon and polyethylene,
results in swelling. Isopropyl myristate is incompatible with hard
paraffin, producing a granular mixture. It is also incompatible with
strong oxidizing agents.
Regulatory Status
Included in the FDA Inactive Ingredients Database (otic, topical,
transdermal, and vaginal preparations). Used in nonparenteral
medicines licensed in the UK. Included in the Canadian List of
Acceptable Non-medicinal Ingredients.
