Isopropyl myristate functions primarily as a skin penetration enhancer and emollient in topical and transdermal formulations. By modulating the stratum corneum barrier, it improves the absorption and bioavailability of topically applied compounds. The compound also shows inhibitory activity against SARS-CoV-2 3CL-Pro protease (7.206% inhibition at 20 μM) and human HDAC6 enzyme (30.53% inhibition). These additional activities suggest potential beyond its conventional use as a formulation excipient. The compound is generally well-tolerated and widely used in products like lotions, deodorants, and hair treatments.

In vitro studies demonstrate that isopropyl myristate is an effective skin penetration enhancer. It improves the absorption and bioavailability of poorly soluble compounds in biologic formulations. The compound shows inhibitory activity against SARS-CoV-2 3CL-Pro protease with 7.206% inhibition at 20 μM and against human HDAC6 enzyme with 30.53% inhibition. In skin permeation studies, isopropyl myristate enhances the delivery of drugs across biological membranes. The compound's emollient properties make it valuable in topical formulations.

In vivo studies show that isopropyl myristate is effective as a penetration enhancer in topical and transdermal formulations. Its inclusion in transdermal formulations aids in the delivery of drugs across biological membranes. In dermatological research, the compound is used in both in vitro skin permeation studies and in vivo studies. The compound is generally well-tolerated in topical applications. The additional enzyme inhibitory activities suggest potential for further in vivo investigation.

The in vitro skin penetration assay for isopropyl myristate uses Franz diffusion cells with human or animal skin membranes. The compound is applied topically at various concentrations (1-100%) and skin permeation of the compound or co-applied drug is measured over time (up to 24 hours). Receptor fluid samples are collected and analyzed by HPLC or LC-MS. Permeability coefficients and enhancement ratios are calculated. For enzyme inhibition assays, SARS-CoV-2 3CL-Pro protease activity is measured using fluorogenic substrates, and HDAC6 activity is measured using fluorogenic deacetylase substrates. IC50 values are determined from dose-response curves.

In vitro cellular assays for isopropyl myristate typically use skin cell lines (e.g., keratinocytes, fibroblasts) to assess cytotoxicity and skin compatibility. Cells are cultured in appropriate media and treated with the compound at concentrations of 0.01-10% for 24-72 hours. Cell viability is assessed using MTT or neutral red uptake assays. Skin irritation potential is evaluated by measuring cytokine release (IL-1α, IL-6, TNF-α) or using reconstructed human epidermis models. Permeation studies use Transwell systems with epithelial cell monolayers. The compound's effects on barrier function are assessed by measuring transepithelial electrical resistance (TEER).

In vivo animal studies for isopropyl myristate involve topical application to animal skin to assess penetration enhancement and skin compatibility. The compound is applied topically to mice, rats, or pigs at concentrations of 1-100% daily for 1-4 weeks. Skin penetration is assessed by measuring drug levels in skin layers and plasma. Skin irritation is evaluated by visual scoring, histopathology, and measurement of skin barrier function (transepidermal water loss). For formulation studies, the compound's effect on drug bioavailability is assessed by measuring plasma drug levels after topical application.

Absorption, Distribution and Excretion
The skin absorption rate of isopropyl myristate is estimated at 0.00020 mg/cm²/dose, which is considered a very low absorption rate. In one study, topically applied isopropyl myristate was primarily retained in the stratum corneum. In in vitro skin penetration assays using human epidermis (stratum corneum and active epidermis) and dermis of varying thicknesses, isopropyl myristate was not detected in the receptor fluid in the flow diffusion pool. There is currently no readily available information on the pharmacokinetics of isopropyl myristate. Four monkeys were exposed to a spray antiperspirant containing a 14C-labeled isopropyl myristate for 5 seconds. Two animals were sacrificed immediately after exposure, and the other two were sacrificed 24 hours later. Distribution of 14C in exhaled gases and several tissues indicated that only 0.25% of the sprayed dose was absorbed in the animals; approximately 10% reached the lower respiratory tract. About 85% of the absorbed isopropyl ester was excreted within 24 hours, primarily as exhaled carbon dioxide; almost no marker reached other tissues except the lungs. In whole-body autoradiography experiments in hairless mice, no penetration of isopropyl ester into the skin or organs was observed, while microautoradiography experiments in guinea pigs showed localized penetration. Isopropyl ester exhibited the highest degree of penetration. Transdermal absorption in Angora rabbits was assessed using microautoradiography, and skin irritation was evaluated histologically. Isopropyl ester was distributed into the skin via the epidermis and hair follicles immediately 24 hours after administration. Isopropyl ester is also considered capable of penetrating human skin, although it is known not to cause erythema on the skin. When isopropyl ester was subcutaneously injected into mice, whole-body autoradiography experiments showed that it was distributed to almost all organs. Liver and kidney extracts were identified as fatty acids and triglycerides. Isopropyl myristate readily distributes to various organs and is metabolized. Metabolites/Metabolites: Any absorbed isopropyl myristate is likely to be hydrolyzed into its constituents, isopropanol and myristic acid. Myristic esters are expected to undergo chemical or enzymatic hydrolysis to produce myristic acid and the corresponding alcohols. Like other high molecular weight aliphatic esters, myristic esters are readily hydrolyzed into the corresponding alcohols and acids, which are then further metabolized. Biological Half-Life: There is currently no readily available information on the pharmacokinetics of isopropyl myristate.
Pharmacokinetic properties of isopropyl myristate indicate it is primarily a topical agent with minimal systemic absorption. The compound has a molecular weight of 270.45 and molecular formula of C17H34O2. It is a colorless, oily liquid. The compound is soluble in organic solvents and has limited water solubility. When used topically, it remains primarily in the stratum corneum and upper skin layers. Minimal systemic absorption occurs. The compound is metabolized to isopropyl alcohol and myristic acid, which are further metabolized and excreted. It should be stored in sealed containers at room temperature.

Protein Binding
Currently, there is no readily available information on the pharmacokinetics of isopropyl myristate. Toxicity Data LC (Rat) > 41,000 mg/m³/1h Interactions The addition of polysorbate 80 to isopropyl myristate solution reduces its permeability constant, especially when these alcohols are initially poorly soluble in their pure solvents. The permeability constants of propylene glycol and water on isolated human skin are 3.2 × 10⁻⁶ cm/hr and 5.5 × 10⁻⁶ cm/hr, respectively. In isopropyl myristate, the permeability constant increases by approximately 250-fold, reaching 1.1 × 10⁻³ cm/hr.

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Non-human toxicity values
Rats oral LD50 >16 mL/kg
Mice oral LD50 49.7 mL/kg
Rats intraperitoneal LD50 79.5 mL/kg
Mice intraperitoneal LD50 50.2 mL/kg
Rabbit skin LD50 5 g/kg

Toxicological data for isopropyl myristate indicates a favorable safety profile for topical use. The compound is generally well-tolerated and widely used in cosmetics and pharmaceuticals. Skin irritation is rare but may occur in sensitive individuals. The compound is not intended for oral administration. For research applications, standard safety precautions should be followed. The compound is for research and formulation purposes only.

[1]. (2012). Study of the influence of the penetration enhancer isopropyl myristate on the nanostructure of stratum corneum lipid model membranes using neutron diffraction and deuterium labelling. Skin Pharmacol Physiol, 25:200-7.

Isopropyl myristate is a fatty acid ester. Isopropyl myristate is a polar moisturizer used in cosmetics and topical pharmaceutical formulations to promote skin absorption. Isopropyl myristate has been extensively studied and promoted as a skin penetration enhancer. Currently, the primary officially approved use of isopropyl myristate is as the active ingredient in over-the-counter lice-killing rinses. Isopropyl myristate has been reported to be found in potatoes (Solanum tuberosum), grosvenorii lice (Siraitia grosvenorii), and other organisms with relevant data. Drug Indications The primary indication for isopropyl myristate as an active ingredient in patient care products is as an over-the-counter lice-killing rinse. FDA Label Mechanism of Action As a lice killer, isopropyl myristate physically covers the lice's exoskeleton. This physical covering subsequently immobilizes the lice and dissolves the waxy layer on the insect's exoskeleton, blocking the insect's respiratory tract and ultimately leading to dehydration and death. Although this physical mechanism of action of isopropyl myristate hardly induces lice resistance (because the mechanism lacks immunological or chemical activity), the substance also lacks ovicidal activity, meaning that any eggs laid by lice will not be affected. Furthermore, isopropyl myristate requires only a 10-minute contact time per administration to exert its lice-killing effect.

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Therapeutic Use
…50% isopropyl myristate cyclomethicone solution (Full Marks Solution - SSL International) is a novel liquid therapeutic agent that uses a physical mechanism of action, requiring only a 10-minute contact time per administration, for the treatment of head lice.
/Experimental Therapy/…A 50% isopropyl myristate (IPM) lice-killing rinse solution has undergone two Phase II clinical trials in North America. The first trial was a non-randomized (proof-of-concept) trial conducted in Winnipeg, Canada, without a control group. The second trial, conducted in the United States, was an evaluator-blinded, randomized, superiority trial comparing the efficacy of 50% isopropyl methylamine (IPM) rinse with a positive control (RID; 0.33% pyrethroid, 4% synergist). The primary endpoint was to determine the safety and efficacy of 50% IPM as a lice-killing rinse. Methods: Eligible subjects were enrolled in the above trial. The efficacy endpoints were observed at 7 and 14 days post-treatment. Erythema and edema were assessed using the modified Draize scale on days 0, 7, 14, and 21. Other information related to safety assessment (e.g., pruritus) was also collected. Results: IPM demonstrated efficacy in both the proof-of-concept study and the controlled trial using a positive control. Imipenem (IPM) was well tolerated with minimal adverse events. All adverse events were mild and resolved by the end of the study. Conclusion: The data suggest that imipenem is a safe and effective treatment for head lice in children and adults. Imipenem's mechanical mechanism of action makes it unlikely to induce resistance.
...Due to their significant advantages such as high drug solubility, good thermodynamic stability, simple preparation, and low cost, microemulsions have a wide range of uses and applications. In recent years, research on microemulsions in the field of transdermal drug delivery has flourished because they can simultaneously encapsulate hydrophilic drugs (such as 5-fluorouracil, apomorphine hydrochloride, diphenhydramine hydrochloride, tetracaine hydrochloride, and methotrexate) and lipophilic drugs (such as estradiol, finasteride, ketoprofen, meloxicam, felodipine, and tripterygium wilfordii), and enhance their permeability...In addition to surfactants, oils can also be used as penetration enhancers (such as oleic acid, linoleic acid, isopropyl myristate, isopropyl palmitate, etc.). ...
/Experimental Therapy/ α-Tocopherol (AT) is a homologue of vitamin E and has the highest in vivo biological activity. AT can protect the skin from ionizing radiation and the carcinogenic and mutagenic effects of chemicals, and may have a protective effect against skin damage caused by ultraviolet radiation. For stability reasons, α-tocopherol is usually used in its prodrug ester form—α-tocopherol acetate (ATA). After absorption through the skin, ATA hydrolyzes to the active form of α-tocopherol. …Permeability studies were conducted using a modified Franz diffusion cell with human cadaver skin as the membrane. Specifically, 5% (w/w) α-tocopherol acetate was formulated into the following carriers: ethanol, isopropyl myristate, light mineral oil, 1% Klucel gel in ethanol, and 3% Klucel gel in ethanol (w/w). …The permeability coefficients of ATA through human cadaver skin were: ethanol solution 1.0 × 10⁻⁴ cm/hr, isopropyl myristate solution 1.1 × 10⁻² cm/hr, light mineral oil solution 1.4 × 10⁻⁴ cm/hr, 1% Klucel gel 2.1 × 10⁻⁴ cm/hr, and 3% Klucel gel 4.7 × 10⁻⁴ cm/hr. The results showed that, except for isopropyl myristate solution, other formulations had little effect on the permeability coefficient of ATA through cadaveric skin. For more complete data on the therapeutic uses of isopropyl myristate (7 formulations in total), please visit the HSDB record page.
Drug Warnings
However, it is essential to carefully examine for potential risks associated with changes in administration method, skin condition, administration site, adjunctive therapies, or excipient composition. Lanolin, cetyl alcohol, myristyl alcohol, sorbitol, isopropyl myristate, and polyethylene glycol (PEG) are substances that can penetrate the skin like the active ingredient… The penetration effect of many penetration enhancers depends on concentration; therefore, the optimal concentration for effective penetration enhancement should be determined. Delivery rates depend on the type of drug, the structure and composition of the carrier, and the characteristics of the membrane used. Each formulation should be carefully examined, as each membrane alters the penetration mechanism and may turn a penetration enhancer into a barrier. People prone to acne continue to use cosmetics. The data provided comes from rabbit ear experiments. While rabbit ear experiments are not ideal animal models, they are the best model we currently have available. If an ingredient tests negative in a rabbit ear experiment, we consider it safe for acne-prone skin. Strongly positive ingredients or cosmetics should be avoided. Non-compliant ingredients include isopropyl myristate and its analogues, such as isopropyl palmitate, isopropyl isostearate, butyl stearate, isostearyl neopentanoate, myristyl myristate, decyl oleate, octyl stearate, octyl palmitate, or isocetyl stearate, as well as newly introduced ingredients in the cosmetics industry, such as propylene glycol-2 (PPG-2) propyl myristate…
…the alternative use of three lipophilic excipients… (medium-chain triglycerides (MG), decyl oleate (DO), and isopropyl myristate (IPM), respectively), with different polarity indices, and their effects on the colloidal structure of alkyl polyglycoside carriers and the in vitro permeation properties of two model drugs: diclofenac sodium (DC) and caffeine (CF) (both poorly soluble in water) were investigated. Changes in lipid-soluble excipients significantly affect colloidal structures, manifesting as different rheological properties and, to some extent, different water distribution patterns, but are particularly influenced by drug properties (amphiphilic electrolyte drugs versus non-electrolyte drugs). In vitro permeation data obtained using ASC membranes in unlimited-dose experiments highlight the importance of carrier/solute interactions when formulation composition changes slightly, indicating that drug properties in the initial hours of permeation and the rheological properties of the carrier in the later stages of the experiment are decisive factors…

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Pharmacodynamics
Isopropyl myristate is an emollient carrier that effectively enhances the permeation of other drugs that can be incorporated as active ingredients into the carrier. In one study, a 50:50 isopropyl myristate binary enhancer synergistically enhanced the transport of estradiol across the human epidermal bilayer in vitro.
Isopropyl myristate (IPM) is a formulation excipient with CAS number 110-27-0. Its molecular formula is C17H34O2 and molecular weight is 270.45. The compound is a polar emollient, solvent, and penetration enhancer used in cosmetics and pharmaceuticals. It improves absorption of poorly soluble compounds in topical formulations. It also shows activity against SARS-CoV-2 3CL-Pro and HDAC6. It is not a drug and is not FDA-approved for therapeutic use.

C17H34O2

270.45

270.255

110-27-0

8042

Colorless to light yellow liquid

0.9±0.1 g/cm3

319.9±0.0 °C at 760 mmHg

-5°C

144.1±8.8 °C

0.0±0.6 mmHg at 25°C

1.440

7.43

0

2

14

19

199

0

O(C([H])(C([H])([H])[H])C([H])([H])[H])C(C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])[H])=O

AXISYYRBXTVTFY-UHFFFAOYSA-N

InChI=1S/C17H34O2/c1-4-5-6-7-8-9-10-11-12-13-14-15-17(18)19-16(2)3/h16H,4-15H2,1-3H3

isopropyl tetradecanoate

FEMA No. 3556 NSC 406280 NSC406280Stepan D-50 Isopropyl myristateHSDB 626 IPM Isomyst NSC-406280

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ~100 mg/mL (~369.75 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (9.24 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: 2.5 mg/mL (9.24 mM) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), suspension solution; with ultrasonication.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (9.24 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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 (Please use freshly prepared in vivo formulations for optimal results.)