Download 2nd Term 13th Lecture

Pharmacology-1 PHL 211
2nd Term
13th Lecture
By
Abdelkader Ashour, Ph.D.
Phone: 4677212
Email: [email protected]
Demulcents,
Overview
 Demulcents:
 Bland compounds of high molecular weight that forms aqueous solutions of high viscosity
which is miscible with the mucus (i.e., It forms viscid mucilaginous solutions with water)
 Demulcent forms a soothing film over a mucous membrane, relieving minor pain and
inflammation of the membrane
 Demulcents as pectin, glycerine, honey and syrup are common ingredients in cough
mixtures
 Actions and uses of Demulcents:
1. Protective action on mucous membranes and abraded skin. They form a layer which
covers the surface of the mucous membrane, thus protecting it against irritant and noxious
stimuli as mucin in case of gastric ulcer
2. Masking the bad taste of drugs through covering the taste buds of the tongue and by
adsorbing drug molecules thus preventing their contact with the taste buds
3. Delaying the absorption of drugs as inclusion of gelatin in the depot form of heparin results
in delayed absorption and prolonged duration
4. Delaying the excretion of drugs as Gum administered with saline delays its excretion
5. Employed as emulsifying and suspending agents
Demulcents,
Examples
 Examples of demulcents:
 Domestically available demulcents as egg white, milk, starch
 Gum Acacia and Gum Tragacanth as emulsifying and suspending agents
 Glycyrrhiza (Liquorice): liquiorice root contains demulcent active principles which may be
employed as a vehicle for expectorant drugs or as flavouring agent
 Carbenoxolone: synthetic derivative of glycyrrhizic acid (extracted from liquorice), used to
promote healing of gastric ulcers (MOA and main side effect???)
 Glycerine: Pure glycerine is applied on mucous membrane as demulcent
 Gelatine: incorporated in the depot form of heparin
Emollients,
Overview
 Emollients:
 Oily or fatty substances (such as lanolin, paraffin) of vegetable, mineral, or animal origin that
forms occlusive film on skin to produce local protection from external irritation and to prevent
water evaporation. This prevents dryness of the skin and decreases heat loss. They are
used as creams, ointments and pastes (i.e., emollients act as protectives and as softening
agents)
 Preparations of emollients:
Vegetable oils as olive oil, almond oil, theobroma oil (cocoa butter)
Animal fats such as lanolin (wool fat): They are absorbed from the skin with the drugs
incorporated in them
Hydrocarbons obtained from petroleum
liquid paraffin (mineral oil): used as a lubricant purgative
Soft paraffin (Vaseline): This substance is not absorbed from the skin and is used as
ointment bases for drugs which are not intended to be absorbed
 Waxes as beeswax (as ointment base)
 Vitamins A and D, in a suitable cream or ointment base, is used topically as a protectant
and/or emollient for various minor dermatologic conditions including diaper rash, chafed skin,
abrasions, and minor burns
Hemostatics,
Overview
 Hemostasis is the cessation of blood loss from a damaged vessel
Platelets first adhere to macromolecules in the subendothelial regions of the injured blood
vessel
Platelets then aggregate to form the primary hemostatic plug.
Platelets stimulate local activation of plasma coagulation factors, leading to generation of a
fibrin clot that reinforces the platelet aggregate.
Later, as wound healing occurs, the platelet aggregate and fibrin clot are degraded
 Hemostatic agent is a substance that promotes hemostasis (stops bleeding)
 Hemostatic agents used in medicine are either:
 Systemic drugs: They work by inhibiting fibrinolysis or promoting coagulation. These include
antifibrinolytics (e.g., aminocaproic acid ), vitamin K, fibrinogen, and blood coagulation
factors
 Locally-acting hemostatic agents (e.g., tannic and): They work by causing vasoconstriction
or promoting platelet aggregation
 Organic: As a kind of hybrid of local and systemic, topical hemostatic bandage D-Stat Dry is
medicated with thrombin coagulation factor:
D-Stat Dry is a topical hemostatic bandage used to control surface bleeding from vascular
access sites following percutaneous procedures. It relies on clotting power of thrombin to
activate clotting factors VII, V and XII
 Styptics are a specific type of hemostatic agents that work by contracting tissue to
seal injured blood vessels. Styptic pencils contain astringents
Astringents
 The word "astringent" derives from Latin adstringere, meaning "to bind fast".
 Definition: Astringent is a drug that reacts chemically with cellular proteins producing
limited coagulation which is accompanied with shrinkage of body tissues.
 Astringent protects from external irritation and reduces cellular permeability
 It also possesses local styptic and local antiseptic actions
 Astringent medicines cause shrinkage of mucous membranes or exposed tissues and
are often used internally to check discharge of blood serum or mucous secretions
 This can happen with a sore throat, hemorrhages, diarrhea, or with peptic ulcers.
Externally applied astringents, which cause mild coagulation of skin proteins, dry, harden,
and protect the skin
 Acne sufferers are often advised to use astringents if they have oily skin
 Examples: very cold water, rubbing alcohol and zinc oxide, and vegetable substances
such as tannic acid
 Uses of astringents:
 Cleaning the face and preventing Acne Breakouts
 Stopping bleeding
 Relieving the discomfort and itching of insect bites, minor abrasions and Athlete’s foot
 Haemorrhoids