🔴Mechanisms of Emulsification

A number of different chemical and physical processes and mechanisms can be involved in the process of emulsification.

🔸Surface tension theory :
-According to this theory, emulsification takes place by the reduction of interfacial tension between two phases.

🔸Repulsion theory:
-The theory proposes that the emulsifying agent creates a film over one phase that forms globules, which repel each other. This repulsive force causes them to remain suspended in the dispersion medium.

🔸Viscosity modification:
-Certain emulgents such as acacia, tragacanth, carboxymethylcellulose, polyethylene glycol, increase the viscosity of the medium, which helps create and maintain the suspension of globules of the dispersed.

🔴MECHANISM

📌G-PROTEIN COUPLED RECEPTOR

▪G protein-coupled receptors (GPCRs), also known as seven transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptors, and G protein-linked receptors (GPLR), form a large group of evolutionary related proteins that are cell surface receptors that detect molecules outside the cell and activate cellular responses. ▪Coupling with G proteins, they are called seven-transmembrane receptors because they pass through the cell membrane seven times.
▪ Ligands can bind either to extracellular N-terminus and loops or to the binding site within transmembrane helices .
▪They are all activated by agonists although a spontaneous auto-activation of an empty receptor can also be observed.
The G-protein coupled receptors expressed in three different ways
▪Gs-Increses the level of CAMP
▪Gi-Decreses levels of CAMP
▪Gq-Increses IP3 DAG

🔸There are two principal signal transduction pathways involving the G protein-coupled receptors:

1.The cAMP signal pathway and

2.The phosphatidylinositol signal pathway.

▪When a ligand binds to the GPCR it causes a conformational change in the GPCR, which allows it to act as a guanine nucleotide exchange factor (GEF).
▪The GPCR can then activate an associated G protein by exchanging the GDP bound to the G protein for a GTP. ▪The G protein's α subunit, together with the bound GTP, can then dissociate from the β and γ subunits to further affect intracellular signaling proteins or target functional proteins directly depending on the α subunit type.

🔴Classification :-
Pharmaceutical Emulsions

🔺1.Simple emulsions

Oil-in-Water (O/W)
Water-in-Oil (W/O)

🔺2.Multiple emulsions

Oil-in-Water-in-Oil
(O/W/O)
Water-in-Oil-in-Water
(W/O/W)

🔺3.Micro emulsions

🔴 Types of Emulsion :-
-Depending upon the nature of the dispersed phase, the emulsions are classified as;

1️⃣ Oil-in-water emulsions (O/W) :

-The emulsion in which oil is present as the dispersed phase and water as the dispersion medium (continuous phase) is called an oil-in-water emulsion. Milk is an example of the oil-in-water type of emulsion. In milk liquid fat globules are dispersed in water. Other examples are, vanishing cream etc.

2️⃣ Water-in-oil emulsion (W/O) :
-The emulsion in which water forms the dispersed phase, and the oil acts as the dispersion medium is called a water-in-oil emulsion. These emulsion are also termed oil emulsions. Butter and cold cream are typical examples of this types of emulsions. Other examples are cod liver oil etc.

🔴ADR:

IDIOSYNCRASY-
•Genetically determined abnormal reactivity to a chemical.
•Certain Bizzare drug effects due to peculiarities of an individual,not found in majority subjects,and produces the uncharacteristic reaction.

E.g.-
•Barbiturates---> Excitment and mental confusion in some individuals.
•Quinine--->Cramps,diarrhea, asthma,vascular collapse in some individuals.
•Chloramphenicol--->Aplastic anemia in rare individuals.

🔴DEFINITION

🔶Emulsion =

An emulsion is mixture of two liquids that would not normally mix. That is to say, a mixture of two immiscible liquids.

🔶Stability of Emulsion =

The ability of an emulsion to retain its properties over time is known as the stability of an emulsion.

🔶Emulsifying agent or Emulsifier =

An emulsifier or emulsifying agent is a compound or substance that acts as a stabilizer for emulsions, preventing liquids that ordinarily don't mix from separating.

🔶 Surfactants =

The agents which are used in the formulations for decreasing the interfacial tension between solid and liquid and hence wetting of the solid occurs.

🔶 DEFINITION

Creaming=

It is the unwanted diffect in the emulsion in which droplets which having low density moves against gravity i.e. on the top of the emulsion.

🔴 Classification

General Classification of
Cosmetics :-

🔺1.Facial Cosmetics

Cleansing preparations, skin nourishing cosmetics, skin tonic, shaving cream, Make up Cosmetics (Face mark, Vanishing cream, powder, multipurpose creams for sports)

🔺2.Hair Cosmetics

Hair Dye, hair oil, hair creams, hair gels, anti-dandruff preparations, hair removing creams, Shampoos etc...

🔺3.Eye Cosmetics

Eye liners, Eye gloves, kajal, Surma, contact lens, eye brow pencils

🔺4.Dental and oral cavity cosmetics

Tooth paste, tooth powder, mouth washes, Gums, teeth whitenings, etc....

🔺5.Antiperspirants

Liquid, lotion, sticks, powder, etc..

🔺6.Deoderants

Powder, liquid, cream, sticks, etc...

🔺7.Nail cosmetics

Nail polish, Nail polish removing liquid, etc...

🔺8.Miscellaneous Cosmetics

Anti-stress mark, Black head removers, etc...

🔴Mechanism

📌Enzyme Linked Receptor :-
•A group of transmembrane proteins that contain either intrinsic enzyme activity on their intracellular domain or associate directly with an intracellular enzyme.
•Upon ligand binding a conformational change is transmitted via a transmembrane helix which activates the enzyme,initiating signaling cascades.

🔹️5 main classes are distinguished by :
•Type of effector(e.g.kinase vs phosphatase)
•Target(Serine/threonine,tyrosine,histidine)
•Type of linkage between receptor and enzyme

●Receptor tyrosine kinase(-RTK)
●Tyrosine kinase linked receptor
●Receptor serine/threonine kinase
●Receptor guanylyl cyclase
●Histidine-kinase associated receptors

➡️Ligands bind to both receptors.
➡️The two receptor polypeptides aggregate forming a dimer.
➡️Activates the tyrosine-kinase parts of the dimer.
➡️Each phosphorylates(using ATP)the tyrosines on the tail of the other polypeptide.
➡️Receptor proteins are now recognized by relay proteins inside the cell.
➡️Relay proteins bind to the phosphorylated tyrosines(may activate 10 or more different transduction pathways).

🔴ADR🔴

📌TERATOGENICITY :-
🔹️Teratology-It is the study of environmentally induced congenital malformations.Congenital malformations are non-reversible functional or morphological defects present at birth.They may not be detectable at birth and only become evident later in life.
🔹️A teratogen is an agent which by acting on the developing embryo or fetus can cause a structural anomaly.
•To date,very few drugs are proven teratogens.However malformations induced by drugs are important because they are potentially preventable.
🔹️Teratogenesis-It is a prenatal toxicity characterized by structural or functional defects in developing embryo or fetus.It also includes intrauterine growth retardation,death of the embryo or fetus and transplacental carcinogenesis(in which chemical exposure of the mother initiates cancer development in the embryo or fetus,resulting in cancer in the progeny after the birth).

🔴ADR🔴

🔷️Intolerance:-
•Appearance of characteristic toxic effects of a drug in an individual at therapeutic doses.
•Converse of tolerance.
•Indicates a low threshold of individual.

✅E.g:-
•Triflupromazine(Single dose)---->Muscular dystonias in some individuals.
•Carbamazepine(Few doses)---->Ataxia in some individuals.
•Chloroquine(Single tablet)---->Vomiting and abdominal pain in some individuals.