Write the differences Between Ointments and Creams
While both are semi-solid preparations for the skin, the choice between an ointment and a cream depends on the hydration level of the skin and the desired absorption rate of the medication.
| Feature | Ointments (Unguenta) | Creams (Cremores) |
|---|---|---|
| Oil-to-Water Ratio | ~80% Oil / 20% Water | ~50% Oil / 50% Water |
| Consistency | Greasy, thick, and viscous. | Lighter, soft, and easy to spread. |
| Absorption | Slow; sits on top of the skin. | Fast; disappears into the skin. |
| Mechanism | Occlusive: Traps moisture in. | Emollient: Softens the skin. |
| Preservatives | Usually none (low water content). | Required (to prevent microbial growth). |
| Best For... | Dry, scaly, or thickened skin. | Oily, weeping, or "wet" skin rashes. |
The "Rule of Dryness":
If the skin is dry, use an ointment to lock in moisture. If the skin is wet or oozing (like a weeping rash), use a cream to allow the skin to breathe and dry out slightly.
Stability and Formulation
Ointments are thermodynamically stable because they are mostly hydrocarbon-based (like Petrolatum). They do not "separate" easily.
Creams are emulsions that require a surfactant to keep the oil and water mixed. Without stabilizers like Cetyl Alcohol or Glyceryl Monostearate, the cream would separate into two distinct layers.