Oral pharma

ISHIK UNIVERSITYFACULTY OF DENTISTRY

Oral Pharmacology
Fall 2016

Dr. Esra Tariq Bayrakdar

Pharmacist (M.Sc.)

• Basic and Clinical Pharmacology, 11th Edition, Bertram G. Katzung, Susan B. Masters, Anthony J. Trevor, McGraw-Hill Medical (2009)
• Pharmacology for Dentistry, Surender Singh, ( 2007)
• Pocket prescribe, 2010, Timothy R.J. Nicholson, Ashan Gunarathne, Donald R.J. Singer
• Drug Prescribing For Dentistry,Dental Clinical Guidance, 3rd edition, Scottish Dental Clinical Effectiveness Programme, 2016.
• British National Formulary (BNF 68), 2014-2015
Required Text Books

Introduction

Prescribing Information
Drug Interactions
Prescribing For Specific Patient Groups
Prescription Writing
Adverse Reactions to Drugs
Medical Emergencies in Dental Practice
Pain Management
Bacterial, Fungal and Viral Infections
Mucosal Ulceration and Inflammation
Dry Mouth
Dental Caries


Outlines of the course

Pharmacology

The science of drugs 
Greek: Pharmacos (drug) + logos (study)
The study of substances that interact with living system through chemical processes, especially by binding to regulatory molecules and activating or inhibiting normal body processes.

Drug

A chemical substance of known structure, other than a nutrient or an essential dietary ingredient, when administered to a living organism, produces a biological effect.
Prodrug ??







Pharmacodynamics deals with physiological and biochemical effects of drugs and their meachanism of action at macromolecular , subcellular, organ, system level.


Pharmacokinetics may be defined as the measurement and formal interpretation of changes with time of drug concentrations in one or more different regions of the body in relation to dosing ('what the body does to the drug') . This distinguishes it from pharmacodynamics ('what the drug does to the body‘
The main two divisions of Pharmacology

A rational approach to this objective combines the principles of pharmacokinetics with pharmacodynamics to clarify the dose-effect relationship.
Pharmacodynamics governs the concentration-effect part of the interaction, whereas pharmacokinetics deals with the dose-concentration part.
The pharmacokinetic processes of absorption, distribution, and elimination determine how rapidly and for how long the drug will appear at the target organ. The pharmacodynamic concepts of maximum response and sensitivity determine the magnitude of the effect at a particular concentration.

Routes of Drug Administration

oral (P.O)
sublingual (SL)
rectal
application to other epithelial surfaces (e.g. skin, cornea, vagina and nasal mucosa)
inhalation
injection
subcutaneous (SC)
intramuscular (IM)
intravenous (IV)
intrathecal
intravitreal

Routes of Drug Administration

Local Routes
The dosage forms applied locally to theskin are powders, paste, lotions, ointments,creams, plasters and jellies. They are used for their antiseptic, antipruritic, analgesic,local anaesthetic and other related effects.


The absorption of drug through the skin is proportional to the surface area covered and to their lipid solubility.
The dermis layer is freely permeable to many fluids. Inflammatory and other related conditions which increase the cutaneous blood flow also enhance absorption of drugs

The topical application is also used on the mucous membranes i.e. nose, throat, eye,ear, bronchi, rectum, urethra, vagina andrectum.
In case of mouth and pharynx, the drug is used in the form of throat paints, lozenges,gargles or mouth washes.

The bronchial mucosa and lungs are treated with inhalations, aerosols (in the formof fine powder with the help of nebulizer) salbutamol (ASTHALIN) inhaler.

ADMINISTRATION BY INHALATION

Inhalation is the route used for volatile and gaseous anaesthetics ,the lung serving as the route of both administration and elimination. The rapid exchange resulting from the large surface area and blood flow makes it possible to achieve rapid adjustments of plasma concentration.

Particles larger than 20 micron and the particles impact in the mouth and throat. Smaller than 0.5 micron and they aren't retained




Drugs used for their effects on the lung are also given by inhalation, usually as an aerosol.
Glucocorticoids (beclometasone dipropionate) and bronchodilators ( salbutamol are given in this way to achieve high local concentrations in the lung while minimising systemic side effects.
However, drugs given by inhalation in this way are usually partly absorbed into the circulation, and systemic side effects (tremor following salbutamol) can occur.
Chemical modification of a drug may minimise such absorption. For example, ipratropium, a muscarinic receptor antagonist


Systemic Routes- Oral Route
Enteric coated tablets: The drugs which are destroyed by the gastric juices in the stomach, arecoated with keratin, shellac and cellulose acid phosphate. These substances are not dissolved by the acid juice of the stomach, but are dissolved in the intestinal juice (alkaline) only.
Preventing gastric irritation and alteration of the drug in the stomach.
To get the desired concentration of the drug in intestine.
To delay the absorption of the drug

Time Release/Sustained Release Capsules: It is a useful solid dosage form of drug, where the particles of the drug dissolve at different time intervals.
Reduction in the frequency of administration of drug
Maintenance of therapeutic effect for longer time.
To some extent decreased incidence of undesired effects.
Appropriate for drugs with short half lives (less than 4 hours)

Sublingual Administration (SL)

The highly lipid soluble and non-irritating drugs. (nitroglycerine) in the form of tablets or pellet is placed under the tongue, where they rapidly dissolve and are absorbed quickly in the general circulation.
The advantages of this routes are:
Rapid onset of action.
The degradation and metabolism of the drugs in the stomach and liver is avoided

Parenteral Route

The advantages of parenteral routes are:
Rapid action of drug.
Can be employed in unconscious/uncooperative patients.
Drugs, which are modified by a limentary juices and liver can be given by this route.
Self medication is difficult.
Chances of local injury at the site of injection
Drugs, which are not absorbed in small intestine or irritate the stomach can be administered by this route.
Disadvantages are:
Less safe, more expensive.
Inconvenient (painful) for the patient

Route for administration -Time until effect-

intravenous 30-60 seconds
intraosseous 30-60 seconds
endotracheal 2-3 minutes
inhalation 2-3 minutes
sublingual 3-5 minutes
intramuscular 10-20 minutes
subcutaneous 15-30 minutes
rectal 5-30 minutes
ingestion 30-90 minutes
transdermal (topical) variable (minutes to hours)

Routes of Drug AdministrationDosage Forms

Solid Dosage forms : includes capsules,granules, effervescent granules, powders,tablets, insufflations, suppositories.
Semisolid/liquid dosage form : elixirs, emulsions, gels, drops, solutions, syrups, creams, enema.
Inhalation forms : aerosols,sprays.
Internal and external uses


Receptor: The component of a cell or organism that interacts with a drug and initiates the chain of biochemical events leading to the drug's observed effects.
It has an important practical consequences for the development of drugs and for arriving at therapeutic decisions in clinical practice.

Drug Receptors

Potency refers to the concentration or dose of a drug required to produce 50% of that drug's maximal effect.

Each drug requires a target within the body (Receptor)

Binding of drugs to receptors could be:
Reversible: Effect for short time (reversible bonding forces)..most drugs.
Irreversible: Effect is prolonged (Covalent bonding forces)..Aspirin causes irreversible inhibition of PG synthesis.
Drug –Receptor Interaction

They act by antagonism or inhibition

Cell surface Receptors
Ion Channels
Enzyme Inhibition
Transport Inhibitors
Nuclear Receptors
How Drugs Act?