Types of Ointment Bases Used in Manufacturing
Ointment bases are the semi-solid vehicles used in the formulation of ointments. They provide a suitable matrix for the active pharmaceutical ingredients (APIs) and play a crucial role in drug delivery through the skin. Various ointment bases are used in pharmaceutical manufacturing, each offering specific properties and advantages. Here are the different types of ointment bases commonly used:
1. Oleaginous Bases
- Oleaginous bases are hydrophobic and primarily composed of greasy or oily substances.
- They are ideal for drugs that are not water-soluble and need prolonged contact with the skin for absorption.
- Examples of oleaginous bases include white petrolatum,
mineral oil, and liquid paraffin.
These bases provide occlusion, which helps retain skin moisture and enhances drug penetration.
2. Absorption Bases
- Absorption bases are water-in-oil (W/O) emulsions with a higher water content compared to oleaginous bases.
- They are less greasy and easier to wash off, making them more suitable for applications where less occlusion is desired.
- Absorption bases allow some water-soluble drugs to be incorporated, enhancing their solubility and absorption.
- Examples of absorption bases include hydrophilic ointment (Hydrophilic Ointment USP) and hydrophilic petrolatum.
3. Water-in-Oil (W/O) Bases
- Water-in-oil bases are emulsions with a higher oil content than absorption bases.
- They are suitable for water-soluble drugs, as the oil phase protects the drug from water and enhances stability.
- Water-in-oil bases provide a greasy feel and are more occlusive, making them suitable for dry skin conditions.
- Common examples of water-in-oil bases include cold cream and hydrophilic ointment cream (Aquaphor).
4. Oil-in-Water (O/W) Bases
- Oil-in-water bases are emulsions with a higher water content than oleaginous bases.
- They are less greasy and easier to wash off, making them suitable for applications requiring quick absorption.
- Oil-in-water bases are ideal for delivering water-soluble drugs and are often used in dermatological formulations.
- Common examples of oil-in-water bases include hydrophilic ointment cream and vanishing cream.
5. Water-Soluble Bases
- Water-soluble bases are not greasy and are washable with water, leaving no residue on the skin.
- They are suitable for delivering water-soluble drugs and for applications where occlusion is not desired.
- Water-soluble bases are often used in ophthalmic and nasal formulations.
- Examples of water-soluble bases include polyethylene glycol (PEG) ointments and hydrophilic ointment gel.
Each type of ointment base offers specific advantages, and the choice of base depends on the drug’s solubility, desired release profile, skin condition, and patient preference. Formulators carefully select the appropriate ointment base to ensure the optimal delivery of the active pharmaceutical ingredient and achieve the desired therapeutic effect.