BP102T • Unit 5Topic 1 of 2⏱ 5 Min Read

1. Semisolid Dosage Forms: Ointments, Creams, Pastes & Jellies

💡 Core Concept & Clinical Context:

Semisolid dosage forms are intended for topical application to the skin or accessible mucous membranes for protective, emollient, or therapeutic purposes. Ointments are greasy, unctuous preparations containing < 20% water and > 50% hydrocarbons/resins. Creams are semisolid emulsions (O/W vanishing creams or W/O cold creams). Pastes contain high concentrations of finely powdered insoluble solids (20% to 50% such as Zinc Oxide paste) creating a stiff, porous, protective barrier that absorbs serous wound exudates. Jellies/Gels are transparent, non-greasy semisolids containing synthetic or natural gelling polymers (Carbopol, Sodium alginate, Methylcellulose).

Clinical Scenarios & Pharmacopoeial Examples:

1Classification of Ointment Bases

Four official USP/IP ointment base classes.

Step-by-Step Breakdown:

•1. Oleaginous / Hydrocarbon Bases: White Soft Paraffin, Yellow Soft Paraffin, Liquid Paraffin. (Highly emollient, greasy, occlusive, difficult to wash with water).

•2. Absorption Bases: Wool Fat (Anhydrous Lanolin), Hydrous Wool Fat, Hydrophilic Petrolatum. (Can absorb large volumes of aqueous liquids to form W/O emulsions).

•3. Water-Removable / Emulsion Bases: Cetomacrogol Emulsifying Ointment, Hydrophilic Ointment USP. (O/W type, easily washed off skin with water, non-greasy).

•4. Water-Soluble Bases: Polyethylene Glycol (PEG) Ointment (Macrogol 400 + Macrogol 4000). (Grease-free, lipid-free, completely washable).

Comparison & Reference Table:

Semisolid Class	Typical Composition	Physical Consistency	Key Therapeutic Application
Ointment	> 50% Hydrocarbons / Soft paraffin	Greasy, occlusive, unctuous	Dry, chronic, scaly skin lesions (Psoriasis, Eczema)
Cream (O/W)	Emulsion with Cetomacrogol	Smooth, non-greasy, vanishing	Acute, weeping skin conditions, cosmetic moisturizers
Paste	20 - 50% insoluble solids (ZnO, Starch)	Stiff, gritty, porous, localized	Diaper rash, weeping sores, sunscreens
Jelly / Gel	Aqueous polymer solution (Carbopol)	Transparent, cooling, non-greasy	Lubricant for catheters, topical NSAID analgesic gels

📋Key Takeaways & Exam Highlights

Trituration Method: Used when medicament is insoluble in base; API is finely levigated using a levigating agent (Liquid paraffin or Glycerin) on an ointment slab before geometric incorporation.
Fusion Method: Used when base contains solid waxes of differing melting points (Beeswax, Hard paraffin, Cetyl alcohol); ingredients are melted in descending order of melting points on a water bath.
Pastes vs Ointments: Pastes contain 20-50% solid powders, are less greasy, more absorbent, and less occlusive than ointments.

🇮🇳 हिन्दी व्याख्या (1. Semisolid Dosage Forms: Ointments, Creams, Pastes & Jellies)

मलहम (Ointment) तैलीय होता है और सूखी त्वचा के लिए उपयोगी है। क्रीम (Cream) पानी से धुलने योग्य होती है। पेस्ट (Paste) में 20-50% सूखा पाउडर होता है जो घावों के रिसाव को सोखता है।