Excipient Profile of Methanol: Literature Review

Excipient Profile of Methanol: Methanol is often referred to as wood alcohol, is a simple alcohol with the chemical formula CH3OH. It is a colorless, volatile, flammable liquid with a slightly sweet odor. While methanol is used in various industrial applications, it is also employed as an excipient in the pharmaceutical industry. However, its use in pharmaceuticals is limited due to its potential toxicity.

Excipient Profile of Methanol: Literature Review

Physical and Chemical Properties: Excipient Profile of Methanol

  • Molecular Weight: 32.04 g/mol
  • Boiling Point: 64.7°C (148.5°F)
  • Melting Point: -97.6°C (-143.7°F)
  • Density: 0.7918 g/cm³ at 20°C
  • Solubility: Miscible with water, ethanol, and most organic solvents.

Methanol: Physical and Chemical Properties

1. Molecular Structure:

  • Methanol has a simple structure, represented by the formula CH3OH. It consists of a methyl group (CH3) bonded to a hydroxyl group (OH).

2. Molecular Weight:

  • 32.04 g/mol

3. Appearance:

  • Methanol is a clear, colorless liquid.

4. Odor:

  • It has a characteristic, slightly sweet odor, reminiscent of alcoholic beverages.

5. Boiling Point:

  • 64.7°C (148.5°F)

6. Melting Point:

  • -97.6°C (-143.7°F)

7. Density:

  • 0.7918 g/cm³ at 20°C

8. Solubility:

  • Methanol is miscible with water, meaning it can mix with water in any proportion. It is also miscible with many organic solvents, including ethanol, acetone, and diethyl ether.

9. Vapor Pressure:

  • 13.02 kPa at 25°C

10. Refractive Index:

  • 1.3284 (20°C)

11. Viscosity:

  • 0.59 cP at 20°C

12. Flash Point:

  • 11°C (51.8°F)

13. Autoignition Temperature:

  • 470°C (878°F)

14. Flammability:

  • Methanol is highly flammable and can form explosive mixtures with air.

15. Acidity (pKa):

  • 15.5, making it a very weak acid due to the presence of the hydroxyl group.

16. UV-Vis Absorption:

  • Methanol does not absorb UV or visible light, making it a common solvent in UV-Vis spectroscopy.

17. Reactivity:

  • Methanol can react with strong oxidizers, acids, and bases. It can also form explosive peroxides upon prolonged exposure to air.

Excipient Profile of Methanol

Molecular StructureCH3OH
Molecular Weight32.04 g/mol
AppearanceClear, colorless liquid
OdorSlightly sweet
Boiling Point64.7°C (148.5°F)
Melting Point-97.6°C (-143.7°F)
Density0.7918 g/cm³ at 20°C
SolubilityMiscible with water and many organic solvents
Vapor Pressure13.02 kPa at 25°C
Refractive Index1.3284 (20°C)
Viscosity0.59 cP at 20°C
Flash Point11°C (51.8°F)
Autoignition Temperature470°C (878°F)
FlammabilityHighly flammable
Acidity (pKa)15.5
UV-Vis AbsorptionDoes not absorb UV or visible light
ReactivityReacts with oxidizers, acids, and bases

Pharmaceutical Uses- Excipient Profile of Methanol

Methanol is primarily used in the pharmaceutical industry as a solvent. It can dissolve a variety of organic compounds, making it useful in the extraction and purification of certain drug components. Some specific uses include:

  1. Extraction Solvent: Methanol can be used to extract specific compounds from plant or animal tissues.
  2. Chromatography: Often used as a mobile phase in thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC).
  3. Organic Synthesis: Methanol can act as a reagent in the synthesis of certain pharmaceutical compounds.

Safety Concerns- Excipient Profile of Methanol

Methanol is toxic when ingested, inhaled, or absorbed through the skin. It can be metabolized in the body to formaldehyde and then to formic acid, both of which are toxic. Symptoms of methanol poisoning include headache, dizziness, nausea, lack of coordination, and a decrease in vision or blindness. In severe cases, it can lead to metabolic acidosis, central nervous system depression, and death.

Due to its toxicity, methanol is not used as an excipient in formulations intended for internal use. Any pharmaceutical application involving methanol requires rigorous purification steps to ensure that no residual methanol remains in the final product.

Regulatory Status- Excipient Profile of Methanol

Given its potential hazards, the use of methanol in pharmaceuticals is strictly regulated. The International Council for Harmonisation (ICH) and other regulatory bodies have set limits on the permissible levels of methanol in final drug products. These limits are typically based on the route of administration and the daily dose of the drug.


While methanol has certain applications in the pharmaceutical industry, its use is limited by its inherent toxicity. It is crucial for pharmaceutical manufacturers to be aware of the risks associated with methanol and to ensure that any products containing it meet stringent safety standards. As with all excipients, the key is to balance the benefits of its use with the potential risks to ensure patient safety.