PROPELLANTS

-The propellant generally is regarded as the heart of the aerosol package.

-In addition to supplying the necessary force to expel the product, the propellant must also act as a solvent and diluent and has much to do with determining the characteristics of the product as it leaves the container.

-Various chemical compounds have been used as aerosol propellants.

-Compounds useful as propellants can be classified as:


1. Liquefied gases
-Chlorofluorocarbons (CFC)
-Hydrochlorofluorocarbons (HCFC)
-Hydrofluorocarbons (HFC)
-Hydrocarbons (HC)
2. Hydrocarbon ethers
3. Compressed gases
-Nitrogen
-Nitrous oxide
-Carbon dioxide


CONTAINERS

•Metal
-TIN-PLATED STEEL
-ALUMINUM
-GLASS

PARTS OF CONTAINER:

•VALVES
-The primary purpose of the valve is to regulate the flow of product from the container.
-Continuous-Spray Valves
A small hole about 0.013 to 0.020􏰇 in diameter sometimes is placed in the valve body.

-Foam Valves
Valves for foam or aerated products usually have only one ex- pansion orifice, the one at the seat.

•ACTUATORS
-The actuator provides a rapid and convenient means for releasing the contents from a pressurized container. It provides the additional functional use in allowing the product to be dispensed in the desired form, that is, a fine mist, wet spray, foam, or solid stream.

•PACKAGING
-Depending on the nature of the product concentrate, the aerosol can be filled by a cold-filling or a pressure-filling process. There are advantages and disadvantages to both methods, and there are many factors that must be considered before deciding which process to use.

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🔴Binding of drugs to receptors🔴

📌•Binding of drugs to receptors necessarily obeys the Law of Mass Action.

📌 •At equilibrium, receptor occupancy is related to drug concentration by the Hill–Langmuir equation

📌•The higher the affinity of the drug for the receptor, the lower the concentration at which it produces a given level of occupancy.

📌•The same principles apply when two or more drugs compete for the same receptors; each has the effect of reducing the apparent affinity for the other.

🔴 DEFINITION

Monophasic liquid =

Monophasic liquid containing two or more components in one phase system.

🔴 DEFINITION

Biphasic liquid =

The liquid which consist of two phases are known as biphasic liquids.
For ex. Emulation , suspension

🔴 DEFINITION

Suspension =

Suspension is a heterogeneous mixture in which the solute particles do not dissolve, but get suspended throughout the bulk of the solvent, left floating around freely in the medium.

🔴 DEFINITION

Flocculated System =

The system in which supernatant quickly becomes clear due to rapid rate of sedimentation.

🔴 DEFINITION

Deflocculated System =

The system in which supernatant will remain cloudy due to slow rate of sedimentation.

🔴Classification of Pharmaceutical Suspensions

🔺1. Based on General Classes

 Oral suspension

 Externally applied suspension

 Parenteral suspension

🔺2. Based on Proportion of Solid Particles

 Dilute suspension (2 to10%w/v solid)

 Concentrated suspension (50%w/v solid)

🔺3. Based on Electro Kinetic Nature of Solid

 Particles

 Flocculated suspension

 Deflocculated suspension

🔺4. Based on Size of Solid Particles

 Colloidal suspension (< 1 micron)

 Coarse suspension (>1 micron)

 Nano suspension (10 ng)

🔴RECEPTORS

🔵TYPES OF RECEPTORS
🔸ION CHANNEL RECEPTORS(Ligand gated ion channel)
🔸G-PROTEN COUPLED RECEPTORS (GPCR'S)
🔸ENZYME LINKED RECEPTORS
🔸NUCLEAR RECEPTORS

📌ION CHANNEL RECEPTORS

♦️MECHANISM :

▪ Ligand-gated ion channels are integral membrane proteins that contain a pore which allows the regulated flow of selected ions across the plasma membrane.
▪Ion flux is passive and driven by the electrochemical gradient for the permeant ions.
▪ The channels are opened, or gated, by the binding of a neurotransmitter to an orthosteric site(s) that triggers a conformational change that results in the conducting state.
▪ Modulation of gating can occur by the binding of endogenous, or exogenous, modulators to allosteric sites.
It mediate fast synaptic transmission, on a millisecond time scale, in the nervous system and at the somatic neuromuscular junction..
▪Such transmission involves the release of a neurotransmitter from a pre-synaptic neurone and the subsequent activation of post-synaptically located receptors that mediate a rapid, phasic, electrical signal (the excitatory, or inhibitory, post-synaptic potential).

EXAMPLES
1. Nicotinic Receptor-Nm, Nn
2.5HT3 Receptor
3.GABA-A Receptor
4.NMDA Receptor