Transcript Topical Preparation Dr. Basavaraj K. Nanjwade M. Pharm., Ph. D Department of Pharmaceutics Faculty of Pharmacy Omer Al-Mukhtar University Tobruk, Libya. E-mail: [email protected] 2014/05/25 Faculty of Pharmacy, Omer Al-Mukhtar.

Topical Preparation
Dr. Basavaraj K. Nanjwade
M. Pharm., Ph. D
Department of Pharmaceutics
Faculty of Pharmacy
Omer Al-Mukhtar University
Tobruk, Libya.
E-mail: [email protected]
2014/05/25
Faculty of Pharmacy, Omer Al-Mukhtar University,
Tobruk, Libya
1
CONTENTS
1.
2.
3.
4.
5.
6.
7.
8.
Structure and function of the skin.
Factors affecting percutaneous absorption.
Drug-vehicle-skin interaction.
Dermatological formulations.
Liquid topical preparations.
Semi-solid topical preparations.
Bases used for topical preparations.
Release of drugs from ointments, creams and
thermodynamics of their diffusion.
9. References.
2014/05/25
Faculty of Pharmacy, Omer Al-Mukhtar University,
Tobruk, Libya
2
Structure of the skin
• Epidermis:
Stratum corneum (Horny cell layer)
 Stratum lucidum (Clear layer)
 Stratum granulosum ( Granular Layer)
 Stratum spinosum (Prickly layer)
 Stratum germinativum
• Dermis:
• Hypodermis or Subcutaneous layer:
2014/05/25
Faculty of Pharmacy, Omer Al-Mukhtar University,
Tobruk, Libya
3
Structure of the skin
• The human skin comprises three tissue layers: the
stratified, avascular, cellular epidermis, the
underlying dermis of connective tissue and
subcutaneous fat.
• Hairy skin contains hair follicles and sebaceous
glands; the glabrous skin of the soles and palms
produces a thick epidermis with a compact stratum
corneum, but there are no hair follicles or sebaceous
glands.
2014/05/25
Faculty of Pharmacy, Omer Al-Mukhtar University,
Tobruk, Libya
4
Structure of the skin
2014/05/25
Faculty of Pharmacy, Omer Al-Mukhtar University,
Tobruk, Libya
5
Structure of the skin
2014/05/25
Faculty of Pharmacy, Omer Al-Mukhtar University,
Tobruk, Libya
6
Structure of the skin
2014/05/25
Faculty of Pharmacy, Omer Al-Mukhtar University,
Tobruk, Libya
7
Functions of the Skin
• The skin performs many varied functions but here we need
consider only some aspects of its containment and protective
roles.
1. Mechanical function
2. Protective function
a. Microbiological barrier
b. Chemical barrier
c. Radiation barrier
d. Heat barrier and temperature regulation
e. Electrical barrier
f. Mechanical shock
2014/05/25
Faculty of Pharmacy, Omer Al-Mukhtar University,
Tobruk, Libya
8
Factors affecting
percutaneous absorption
 Physico chemical properties of parent molecule
 Solubility and partition co- efficient
 pH condition
 Penetrant concentration
 Physico chemical properties of drug delivery system
 Release characteristic
 Composition of drug delivery system
 Permeation enhancer used
2014/05/25
Faculty of Pharmacy, Omer Al-Mukhtar University,
Tobruk, Libya
9
Factors affecting
percutaneous absorption
 Physiological and pathological condition of skin
 Lipid film
 Skin hydration
 Skin temperature
 Effect of vehicle
 Pathological injury to skin
 Biological factors
 Skin age
 Thickness of S. Corneum
 Skin condition
2014/05/25
Faculty of Pharmacy, Omer Al-Mukhtar University,
Tobruk, Libya
10
Factors affecting
percutaneous absorption
Chronic use of certain drugs
Presence of hair follicles
Blood flow
Regional skin sites
Species difference
2014/05/25
Faculty of Pharmacy, Omer Al-Mukhtar University,
Tobruk, Libya
11
Drug-vehicle-skin
interaction
• Patients also tend to favour creams rather than gels or
ointments.
• Select a vehicle that promotes healing and does no
further damage, as it to apply a therapeutic agent.
• Most vehicles are blended from one or more of three
main components-aqueous solvents, powder and oiltogether with thickening and emulsifying agents,
buffers, antioxidants, preservatis, colours, propelants
etc.
2014/05/25
Faculty of Pharmacy, Omer Al-Mukhtar University,
Tobruk, Libya
12
Dermatological formulations
1.
2.
3.
4.
5.
6.
7.
Liquid preparations
Gels (jellies)
Powders
Ointments
Creams
Pastes
Aerosols
2014/05/25
Faculty of Pharmacy, Omer Al-Mukhtar University,
Tobruk, Libya
13
Liquid topical preparations
• Liquid preparations for external application include
simple soaks or baths, applications, liniments, lotions,
paints, varnishes, tinctures, and ear drops.
• A simple soak provides an active ingredient in aqueous
solution or suspension, sometimes with water-miscible
solvents.
• Gums and gelling agents may vary the consistency, from
mobile liquids to stiff ringing gels.
• Bath additives such as Oilatum Emollient deposit a layer
of liquid paraffin on the stratum corneum in an attempt to
maintain its moisture content by occulsion.
2014/05/25
Faculty of Pharmacy, Omer Al-Mukhtar University,
Tobruk, Libya
14
Semi-solid
topical preparations
• Gels (jellies) are two-component semisolid systems
rich in liquid.
• Their one characteristic feature is the presence of a
continuous structure providing solid like properties.
• In a typical polar gel, a natural or synthetic polymer
builds a three-dimensional matrix throughout a
hydrophilic liquid.
• Ointments are greasy, semisolid preparations, often
anhydrous and containing dissolved or dispersed
medicaments.
2014/05/25
Faculty of Pharmacy, Omer Al-Mukhtar University,
Tobruk, Libya
15
Bases used for topical
preparations
• Hydrocarbon bases: These usually consist of soft
paraffin or mixtures with hard paraffin.
• Fats and fixed-oil bases: Dermatological vehicles
have frequently contained fixed oils of vegetable
origin, consisting essentially of the mono-, di- and
triglycerides of mixtures of saturated and unsaturated
fatty acids.
• Silicones bases: Dimethicones, or dimethyl
polysiloxanes, have properties similar to hydrocarbon
bases.
2014/05/25
Faculty of Pharmacy, Omer Al-Mukhtar University,
Tobruk, Libya
16
Bases used for topical
preparations
• Absorption bases: Absorption bases soak up water
to form water-in-oil emulsions while retaining their
semisolid consistencies.
• Emulsifying bases: These essentially anhydrous
bases contain oil-in-water emulsifying agents which
make them miscible with water and so washable or
‘self-emulsifying’.
• Water-soluble bases: Formulators prepare watersoluble bases from mixtures of high and low
molecular weight polyethylene glycols (macrogols,
carbowaxes)
Faculty of Pharmacy, Omer Al-Mukhtar University,
2014/05/25
17
Tobruk, Libya
Release of drugs from ointments, creams
and thermodynamics of their diffusion
• Partitioning of the medicament between the emulsion
phases.
• The addition of preservatives.
• Determination of a true viscosity for the diffusing
molecules in the vehicle.
• The possibility of phase inversion or cracking of the
emulsion when applied to the skin.
• Drug may also be trapped in the micelles and the gel
and liquid crystalline phases present in the continuous
phase.
2014/05/25
Faculty of Pharmacy, Omer Al-Mukhtar University,
Tobruk, Libya
18
THANK YOU
e-mail: [email protected]
2014/05/25
Faculty of Pharmacy, Omer Al-Mukhtar University,
Tobruk, Libya
19