Liniments

These are alcoholic or oleaginous preparations of various medicinal substances intended for external application to the skin generally with friction and rubbing These are liquid or semi-liquid preparations and can be solution, suspension, or emulsion.

Uses

• They are administered to an area to produce congestion or redness due to their rubefacient activity.
• Irritant: does not directly affect the tissues but causes inflammation of the area to which it is applied.
• Counterirritant: Rubbed intact skin to lessen or ease a tingling or soreness in the area.
  Penetrating behavior
  

Two types of vehicles

1. Alcoholic or hydro-alcoholic vehicle is useful when rubefacient, counter-irritant, or penetrating action is desired.

2. Oleaginous vehicles are employed when massage is desired. They are less irritating than alcoholic liniments

Precautions

It is not recommended to apply liners to injured skin as they may create significant irritation.

Storage and Labeling

• The bottle should be labeled: "For external use only".
• They should be stored in tightly closed containers
• The container must bear a label "Shake the bottle well before use"

MAGMAS

They are aqueous suspensions of insoluble inorganic drugs. Differ from cells that the suspended particles are larger. They are thick or viscous, so suspending agents is unnecessary except for dihydroxy aminoacetate magma, which contains suspending agents in addition to suitable preservatives and flavorings agents.

PREPARATION

1. By simple hydration 2.By chemical reaction

2. Bentonite magma, USP

Aerosols

Aerosols are pressurized dosage forms containing one or more than one active ingredient which upon actuation emit a fine dispersion of solid and quid in gaseous form.

The liquid or solid drug particles are dissolved or suspended in gas. The gas used for this purpose is known as propellant.

Components of Aerosols are:

1. Propellant

2. Container

3. Valve assembly and actuator

4. Product concentrate

1. Propellants

These are chemical substances that are responsible for developing pressure within a container and expelling the product when the valve is open. Commonly used propellants

Butane, isobutane, Chlorofluorocarbons( difluoroethane, dichloro tetrafluoromethane)

2. Containers

Containers are available in tin plate, aluminum, stainless steel, and glass materials.

3. Valve Assembly

The function of the valve assembly is to permit the expulsion of contents of containers

• In the desired form
• In the proper amount or dose

It has the following parts

1. Mounting cup

Used to attach the valve properly to the container, made of tin. Aluminum can also be used.

2. Housing

It contains an opening at the point of attachment of dip tube. It is made of nylon.

3. Stem

It supports the actuator and delivers the product in proper form. Made of nylon, brass and steel.

4. Gas Kat

It is used to prevent leakage of formulation from the container. Made of rubber.

5. Spring

Used to hold the gasket in place. When the actuator is depressed and released it returns the valve to its closed position again.

6. Dip tube

It is used to bring formulation from a container. Its diameter varies from formulation to formulation.

7. Actuator

• Spray actuator: a device that disperses product into minute particles.
  
• Foam actuator (Large orifice)
• Solid actuator (used for semi-solid goods; relatively big aperture)
  
• Specially designed actuator (For appropriate sites such as nasal, throat, and eye)

Metered Valve

These are valves that allow a specific amount of product to come out and then stop automatically. These valves have a reservoir with a set capacity that, when activated, drains all of its contents with a single actuator push.