CAS: 9006‑65‑9 ｜ Monographed in Volume IV of the Chinese Pharmacopoeia (ChP) ｜ Category: Pharmaceutical excipient (defoaming agent, lubricant)
1. Product Overview
Dimethicone is a synthetic liquid-to-semi-solid polymeric compound. Due to its physiological inertness, excellent chemical stability, electrical insulation properties, resistance to both high and low temperatures, flexibility, and lubricating properties, it is widely used in applications such as defoaming, electrical insulation, mold release, paints, waterproofing, dustproofing, and lubrication.
2. Basic Product Information
1) Product Name: Dimethicone
2) CAS NO.: 9006-65-9
3) Molecular Formula: C6H18OSi2
4) Molecular Weight: 162.37752
5) Structural:
1) Product Name: Dimethicone
2) CAS NO.: 9006-65-9
3) Molecular Formula: C6H18OSi2
4) Molecular Weight: 162.37752
5) Structural:
6) Purity: 97.0%‑103.0%
7) Appearance: Colorless, clear, oily liquid, odorless and tasteless
8) refractive index: n20/D 1.406
9) Density: 1 g/mL at 20 °C
10) Solubility: Insoluble in water and ethanol; readily soluble in nonpolar solvents such as chloroform and toluene
11) Flash Point: 121 °C
12) Product Manager Email: Nicole@coreychem.com
3. Frequently Asked Questions (FAQ)
Question 1: What is Dimethicone? What are its basic properties and solubility?
Dimethicone is polydimethylsiloxane, CAS No. 9006‑65‑9, monographed in Volume IV of the Chinese Pharmacopoeia and classified as a pharmaceutical excipient (defoaming agent, lubricant). It is a clear, colorless oily liquid, odorless and tasteless.
In terms of solubility, it is practically insoluble in water and ethanol, and freely soluble in non-polar solvents such as chloroform and toluene.
Its pronounced chemical inertness and good thermal stability provide the foundation for its behavior in formulation
Question 2: Why does the pharmacopoeia classify it by kinematic viscosity at 25℃?
Viscosity reflects the polymer chain length (degree of polymerization) and is the most critical quality attribute and selection criterion for Dimethicone. The pharmacopoeia specifies 10 viscosity grades based on kinematic viscosity at 25℃ (mm²/s, cSt): 20, 50, 100, 200, 350, 500, 750, 1000, 12500, and 30000, grouped into three application bands: low viscosity 20–500 for creams, aerosols, defoaming, and lubrication; medium viscosity 750–1000 for oral emulsions and process defoaming.
Viscosity reflects the polymer chain length (degree of polymerization) and is the most critical quality attribute and selection criterion for Dimethicone. The pharmacopoeia specifies 10 viscosity grades based on kinematic viscosity at 25℃ (mm²/s, cSt): 20, 50, 100, 200, 350, 500, 750, 1000, 12500, and 30000, grouped into three application bands: low viscosity 20–500 for creams, aerosols, defoaming, and lubrication; medium viscosity 750–1000 for oral emulsions and process defoaming.
Question 3: What key tests and assay limits does the pharmacopoeia specify for it?
The key tests include: acidity/alkalinity, loss on drying, heavy metals, arsenic, mineral oil, and phenyl compounds; identification is performed by infrared (IR) spectrophotometry; and the assay is determined by attenuated total reflectance infrared (ATR-IR) spectrometry, requiring the polydimethylsiloxane content to be within 97.0%–103.0%.
The key tests include: acidity/alkalinity, loss on drying, heavy metals, arsenic, mineral oil, and phenyl compounds; identification is performed by infrared (IR) spectrophotometry; and the assay is determined by attenuated total reflectance infrared (ATR-IR) spectrometry, requiring the polydimethylsiloxane content to be within 97.0%–103.0%.
Question 4: How safe is it? What distinguishes the pharmaceutical grade from the industrial grade?
Its safety rests on two points. First, it is virtually not absorbed via the gastrointestinal tract or through the skin, hardly enters the bloodstream, and is excreted unchanged, resulting in extremely low systemic toxicity—suitable for both oral and topical use. Second, the pharmaceutical grade must comply with all pharmacopoeial impurity limits (heavy metals, arsenic, mineral oil, etc.).
Its safety rests on two points. First, it is virtually not absorbed via the gastrointestinal tract or through the skin, hardly enters the bloodstream, and is excreted unchanged, resulting in extremely low systemic toxicity—suitable for both oral and topical use. Second, the pharmaceutical grade must comply with all pharmacopoeial impurity limits (heavy metals, arsenic, mineral oil, etc.).
Question 5: Is pharmaceutical-excipient Dimethicone the same as medicinal Dimethicone?
As a pharmaceutical excipient, Dimethicone is a raw material for formulation manufacturing, serving only the process and the dosage form.
As a pharmaceutical excipient, Dimethicone is a raw material for formulation manufacturing, serving only the process and the dosage form.
When Dimethicone is used as the active ingredient in dimethicone tablets, powders, or emulsions for therapeutic purposes (e.g., gastrointestinal defoaming), it is a medicinal product governed by drug standards and no longer an excipient.
4. Application Cases
1) Dimethicone is a defoaming agent for oral and topical processes.
It eliminates foam in fermentation, extraction, suspension, and emulsion manufacturing (process defoaming only, as an excipient), and reduces bubble defects in creams and gels.
It eliminates foam in fermentation, extraction, suspension, and emulsion manufacturing (process defoaming only, as an excipient), and reduces bubble defects in creams and gels.
2) Dimethicone is a lubricant and mold-release agent.
It enables clean demolding of suppositories and drop pills, prevents punch adhesion in tablet compression, and improves spreading with moisture protection in film coating.
It enables clean demolding of suppositories and drop pills, prevents punch adhesion in tablet compression, and improves spreading with moisture protection in film coating.
3) Dimethicone is a topical base and film former.
It improves the spreadability and skin feel of ointments and creams and forms a hydrophobic protective film on the skin for topical and transdermal preparations.
It improves the spreadability and skin feel of ointments and creams and forms a hydrophobic protective film on the skin for topical and transdermal preparations.
4) Dimethicone provides process and device lubrication.
It lubricates medical-device tubing and supports auxiliary roles such as anti-sticking throughout manufacturing.
It lubricates medical-device tubing and supports auxiliary roles such as anti-sticking throughout manufacturing.
5) Viscosity grade selection follows each dosage form.
Dosage form / Use Recommended viscosity (cSt)
Creams, ointments 100–350
Process defoaming 750
Coating, glidant 20–100
Suppository / ophthalmic ointment bases 12500, 30000
Dosage form / Use Recommended viscosity (cSt)
Creams, ointments 100–350
Process defoaming 750
Coating, glidant 20–100
Suppository / ophthalmic ointment bases 12500, 30000
5. Safety and Storage
Storage: Storage Keep in tightly closed containers, stored in a cool, dry place away from high temperature and contamination.
Storage: Storage Keep in tightly closed containers, stored in a cool, dry place away from high temperature and contamination.
Different viscosity grades should be stored separately with clear labeling to prevent mix-ups, and pharmaceutical-grade material must be strictly segregated from industrial-grade silicone oil.
6. Product Manager Information
Product Manager: Nicole Zhao
Email: Nicole@coreychem.com
Product Manager: Nicole Zhao
Email: Nicole@coreychem.com
