Pharmaceutical Semisolid dosage forms

Pharmaceutical Semisolid dosage forms

Pharmaceutical Semisolid dosage forms are dermatological products of semisolid consistency and applied to skin for therapeutic or protective action or cosmetic function. 

Pharmaceutical Semisolid dosage forms are usually intended for localized drug delivery.

In the past few years, however,  these forms also have been explored for the systemic delivery of various drugs.

Semisolids constitute a significant proportion of pharmaceutical dosage forms.

They can be applied topically to the skin, cornea, rectal tissue, nasal mucosa, vagina, buccal tissue, urethral membrane, and external ear lining.  Eg: Ointments, creams, jellies and pastes etc.

Advantages of Pharmaceutical semisolid dosage form:

·        It is used externally

·        The probability of side effects can be reduced

·        First, pass gut and hepatic metabolism is avoided.

·        Local action and Site-specific action of the drug on the affected area.

·        Convenient for unconscious patients or patients to have difficulty in oral administration.

·        Suitable dosage form for bitter drugs.

·        More stable than a liquid dosage form.

Disadvantages of Pharmaceutical semisolid dosage form:

·        The accuracy can’t be measured, for the semisolid dosage form.

·        May cause staining.

·        They are bulky to handle.

·        Application with a finger may cause contamination.

·        Physico-chemical is less stable than a solid dosage form.

·        May cause irritation or allergy to some patients

Ideal properties of Pharmaceutical semisolid dosage forms:

·        Smooth texture

·        Elegant in appearance

·        Non-dehydrating

·        Non-gritty

·        Non-greasy and non-staining

·        Non-hygroscopic

Ingredients needed for Pharmaceutical semisolid dosage form:

·        Bases

·        Preservative

·        Humectants

·        Antioxidants

·        Emulsifier

·        Gelling agent

·        Permeation enhancer

·        Buffers

Bases used in Pharmaceutical semisolid dosage form:

It is one of the most important ingredients used in the formulation of the semisolid dosage form. Ointment bases do not merely act as the carriers of the medicaments, but they also control the extent of absorption of medicaments incorporated in them.

Ideal characterization of bases used in Pharmaceutical semisolid dosage form:

They should be:

·        Inert, non-irritating, and non-sensitizing.

·        Compatible with skin pH and the drug.

·        Good solvent and/or emulsifying agent.

·        Emollient, protective, non-greasy and easily removable.

·        Release medicament readily at the site of application.

·        Pharmaceutically elegant and possess good stability

Classification of Bases:

According to USP ointment bases are classified into four general groups:

·        Hydrocarbon bases (oleaginous bases) (Petrolatum, Paraffin, Lanolin, etc.)

·        Absorption bases (cold cream, anhydrous lanolin, etc.)

·        Water-removable bases ( oil in water)

·        Water-soluble bases (polyethylene glycol)

Antioxidants used in Pharmaceutical semisolid dosage form:

Oxygen has the capability to become a part of potentially damaging molecules called “free radicals.” Free radicals can attack the healthy cells of the body. It can break their structure and that’s why the function is also affected.

Example: Butylated hydroxyanisole, Butylated hydroxytoluene

Ingredients that increase permeation:

Skin can act as a barrier. There are various penetration enhancers that can help the drug to penetrate through the skin.

Oleic acid

The emulsifier used in Pharmaceutical semisolid dosage form:

Emulsifiers are used to improve the stability of an emulsion by increasing its kinetic stability. It reduces surface tension and prevents coalescence. It helps to increase the viscosity at low concentration.

Sodium lauryl sulfate: Oil/Water emulsion – Sodium stearate and calcium stearate.

Glyceryl monostearate: This is a weak Water/Oil emulsifying agent and it is used as a stabilizer and emollient in the Oil/Water emulsion.

Humectant used in Pharmaceutical semisolid dosage form:

The humectant is a hygroscopic substance used to increase the solubility of the active ingredient to increase skin penetration. It’s also used to improve the hydration of the skin.

Buffers used in Pharmaceutical semisolid dosage form:

Buffers are added for various purposes. Such as

·        Compatibility with skin.

·        Drug solubility.

·        Drug stability.

·        Influence the ionization of drugs.

Preservatives used in Pharmaceutical semisolid dosage form:

Preservatives are used to inhibit the growth of contamination of microorganisms.

Example: Para-hydroxybenzoate (parabens), phenols, benzoic acid, sorbic acid, etc.

Pastes:

·        Pastes are basically ointments containing high percentage of insoluble solids (usually 20-50 % or higher). They are semisolid preparations intended for external application. Pastes are generally very thick and stiff.

·        They have good adhesion on skin and they form thick coat. They are used mainly as antiseptic, protective or soothing dressing.

Ointments:                                                                            

·        Ointments are semisolid preparations with or without medicaments intended for application to the skin.

·        Medicaments used in the formulation is dissolved, suspended or emulsified in an ointment base.

·        The ointments are mainly used as protective or emollient for the skin.

·        Ointments may be used as-

1.      Antibiotic ointments. Drug used: Neomycin.

2.      Antifungal ointment. Drug used: Benzoic acid, salicylic acid, nystatin.

3.      Anti-inflammatory ointment. Drug used: hydrocortisone, etc

ENVIRONMENT Temperature: 20-300 C, Humidity: 30-60 %,

DOCUMENTS: 1. Standard Operating Procedure (SOP)

2. Batch Manufacturing Record (BMR)

3. Batch Packaging Record (BPR)

4. In House specification

Creams:

·         These are viscous semisolid emulsions which are meant for external use. They usually contain a water soluble base due to which they can be easily removed from the skin.

·         They are of softer consistency and have light weight in comparison to true ointments when applied to the skin. Cream leave no visible evidence of their presence on the skin.

·         They are of mostly two types

1. Aqueous cream, Eg: Cetrimide Cream B.P
2. Oily cream, Eg: Proflavine cream BPC

Gels and Jellies:

·        Gels and jellies are transparent to opaque semisolid preparations meant for external application to the skin or mucous membrane.

·
Considered to be more rigid than jellies. Jellies contain more fluid and less cross-linking agent.

·        They are non-greasy and prepared from

·        Natural gums, eg: Tragacanth, Pectin, Sodium Alginate etc.

·        Synthetic derivatives of natural substances, eg:  Methyl cellulose, Sodium carboxymethyl cellulose.

Poultices:

·        Poultices are viscous pasty preparations applied hot to the skin to reduce inflammation and to act as counter irritant.

·        Heavy kaolin is commonly included in the formulation because it act as a carrier of heat. It is an outdated preparation. 

Suppository:

Suppository is another way to deliver drugs.

It’s a small, round or cone shaped object that put in body orifice, often into bottom.

Once its inside, its melt and dissolves and releases the medicine and exert local or systemic effects.

Type of suppository

There are three type of suppository

Rectal Suppository – into the rectum.

Vaginal Suppository – into the vagina.

Urethral Suppository– into male urethra.

ADVANTAGES OF SUPPOSITORIES

Over Oral Drug Administration:

·        Avoid first pass metabolism

·        Introduce drugs into the body

·        Does not cause nausea and vomiting due to gastric irritation in case of oral therapy

·        Used before surgery since oral therapy is restricted

·        Beneficial for patients suffering from severe vomiting

·        Can be administered to unconscious patients

·        Can be used as targeted drug delivery system

·        Localized action with reduced systemic distribution

·        Get to site of action with lower dose reducing systemic toxicity

·        Highly beneficial in haemorrhoids or vaginal infections

·        Prolonged drug action achieved

Over parenteral drug administration:

·        Self-medication

·        No systemic side effects

·        No pain or site of action related issues

Over Vaginal Tablets:

·        Suppositories dissolves faster

·        Total bioavailability achieved

·        No residue remains like tablet

·        No need of applicator

·        Non staining

·        Non itching

DISADVANTAGES OF SUPPOSITORIES:

·        Mucosal irritation

·        Patient compliance

·        Erratic and undesired absorption

·        Placement too high into rectum may lead to first pass metabolism

·        Installation may trigger defecation reaction

·        GI state affects absorption

·        Diarrhoea & disease states affect absorption

 Pharmaceutical Semisolid dosage forms notes pdf