Definition of Pharmacology

Pharmacology is the study of the interactions that occur between our body and chemicals. Knowing

more about the action and uses of a drug.

Importance of Pharmacologyto OHT

• Knowledge of how and when the drug is administered

• Improve patient experience

• Increase the efficiency of dental procedures

• Provide clear explanation of drug to patient (only when prescribed)

• Improve infection control and prevent fatality

HOW PHARMACOLOGY IS INCORPORATED IN DAILY PRACTICES?

WHAT TYPE OF SCENARIOSCAN WE FACE?

Medications/ Ulcer Creams/ Local Anesthesia

MEDICATIONS

Medication/ Ulcer Creams/ Local Anesthesia

MEDICATIONSMedication/ Ulcer Creams/ Local Anesthesia

In what situations is medication incorporated to the job of a OHT?

Almost everyday!When taking medical history

we need to be aware of diseases that the patient might have. Especially if poses any risks during dental procedures.

MEDICATIONSMedication/ Ulcer Creams/ Local Anesthesia

In what situations is medication incorporated to the job of a OHT?

When treating patients who are at high risk of infective endocarditis, sudden bacteremia may be produced by dental manipulation within the mouth.

MEDICATIONSMedication/ Ulcer Creams/ Local Anesthesia

Who are at high risk of infective endocarditis?

Congenital Heart

Disease

Rheumatic

Heart Disease

Congenital

Heart Disease

MEDICATIONSMedication/ Ulcer Creams/ Local Anesthesia

So, when treating such patients…

To get approval from doctor Example of common medication

given is antibiotics-amoxillin. Better absorbed, following oral

administration Amoxicillin is one of the most

common antibiotics prescribed for children

MEDICATIONSMedication/ Ulcer Creams/ Local Anesthesia

In a dental clinic

ULCER CREAMS

When a patient walks in to a clinic…

1. We need to identify the cause of the ulcer

2. Consider treating it3. Prescribe ulcer cream

Medication/ Ulcer Creams/ Local Anesthesia

Medication/ Ulcer Creams/ Local Anesthesia

And now, an advertisement

ULCER CREAMSMedication/ Ulcer Creams/ Local Anesthesia

When local anesthesia is used?

Extraction of teeth Removal of Gum PolypCavity Preparation

LOCAL ANESTHESIAMedication/ Ulcer Creams/ Local Anesthesia

Medication/ Ulcer Creams/ Local Anesthesia

A live extraction in class

LOCAL ANESTHESIAMedication/ Ulcer Creams/ Local Anesthesia

ACTIVITYPurpose/ Route of Entry/ Packaging/ Form of Medicine

USES OF DRUGS

• Also known as antibacterials• Organic substances either produced by micro-organisms or

synthetically manufactured• Drugs used to treat infections caused by bacteria• Inhibit growth of bacteria and other micro-organisms• Not effective against viruses

Uses of DrugsANTIBIOTICS

Antiseptics & Disinfectants

• Basic tools of cleaning and sanitizing

• Eliminate disease-causing organisms

Uses of Drugs

Haemostatics & Styptics

• Blood clotting agents• Arrest the flow of blood

(clotting)• Promote vasoconstriction

ANTISEPTICS & DISINFECTANT /

HAEMOSTATICS & STYPTICS

Pain & Pain Control

• Manage and subdue pain faced by patience

• Provide ease to operator to carry out procedure

Uses of Drugs

Vasoconstriction drugs

• Blanching of tissues• Narrows blood vessels

Pain & Pain Control / Vasoconstriction

ROUTE OF ADMINISTRATION

Internal/ External

Route of Entry

External Route

On the skinMucous

membrane of mouth

Mucous membrane of

rectum

Internal Route

Ingestion, Oral Route Injection

Inhalation

EXTERNAL ROUTE

Internal/ External

External Route

• Applied on the surface: local effects only.

• Depending on chemical structure and quantity applied

• Can be absorbed by the skin and mucous membrane

• Greatest Penetration: drugs with low molecular weight with a high water and lipid solubility

Point of Entry Examples

On the skin Creams, Lotions

On the mucous membrane of mouth

Lozenges, Gargles

On the mucous membrane of rectum

Suppositories

External Route

INTERNAL ROUTE

Internal/ External

Internal Route

1) Ingestion or Oral Route

a. In the mouth, some drugs are readily and rapidly absorbed via the mucous membrane in the mouth

b. In the stomach and small intestine, drugs that are swallowed are absorbed through the lining mucosa

Internal Route

2) Injection

a) Intradermal – in the layers of the skinb) Subcutaneous – into the undersurface of the skinc) Intramuscular – into the deep-seated musclesd) Intravenous – into the veinse) Intraspinal – into the spinal space

Internal Route

3) Inhalation

• Drugs in the form of vapor may be inhaled into the lungs.

• Very small molecular structure and pass easily through the thin epithelium.

• Absorbed through pulmonary endothelium at alveoli to gain rapid access to the general circulation

PACKAGING

• To carry the product and keep it stable, till it is consumed

• Transparent capsules & syrup in a transparent glass bottle is preferred a lot more

• They are not only attractive but are also more trustworthy because patients can “see” what they are consuming

• Most manufacturers are no longer hiding the medicines behind opaque covers

FORM OF MEDICINE

• Many tablets today are coated after being pressed. Some coatings are just to provide colour or a smooth finish, or to facilitate printing on the tablet

• Some tablets have coatings which is designed to hold the tablet together when it is in the stomach

• The coating is designed to hold together in acid conditions and break down in non-acid conditions and therefore release the drug in the intestines

• Example: Aspirin• An enteric coating is

there usually for a good reason and therefore such tablets or the contents of enteric coated capsules should never be crushed before being taken.

• Hard-shelled capsules, which are normally used for dry, powdered ingredients or miniature pellets

• Soft-shelled capsules, primarily used for oils and for active ingredients that are dissolved or suspended in oil

• Solutions, syrups and mixtures• Commonly used in patients that have difficulty

swallowing medicines like children and the elderly• The liquid medicine should be made such that the

dose needed will be a sensible volume such as 5ml (one teaspoon)

ACTIVITYPurpose/ Route of Entry/ Packaging/ Form of Medicine

PURPOSE ROUTE OF ENTRY

PACKAGING FORM OF MEDICINE

1. Antiseptics

2. Pain control

3. Haemostatics

and Styptics

4. Antibiotics

5. Vasoconstriction

External route

1. Skin

2. Oral Mucosa

3. Membrane of

rectum

Internal Route

1. Ingestion

2. Injection

3. Inhalation

1. Hard shelled

Capsules

2. Soft Shell

Capsules

3. Liquid

4. Coated Tablets

1. Blister

Pack

2. Bottle

3. Tube

ABSORPTION OF DRUG

Absorption

ALVEOLI

Absorption of Drug

• Absorption is the process by which a drug passes from its site of administration into the circulation (bloodstream).

• The blood receives a drug from the site of administration and carries it to all the organs, including those on which the drug acts.

• The speed, ease, and degree of absorption are related to the route of administration.

Absorption of Drug

• The absorption rates of drugs depend on its physical and chemical properties, on the site of absorption and the solubility of drug.

Site of Absorption Rate of Absorption

In mucous membrane Rapid

In small intestine Depends on health of stomach and its activity and presence/absence of food

Subcutaneous and Intramuscular injections

Depends on water solubility of drug, dose form and blood supply at site.

Intravenous Injection Immediate

Inhalation Immediate

DISTRIBUTION OF DRUG

Distribution of Drug

• After the drug is absorbed, it is then distributed to various organs of the body.

• Influenced by how well each organ is perfused, organ size, binding of the drug to various components of blood and tissues, and permeability of tissue membranes.

• The more fat-soluble a drug is, the higher its ability to pass across the cell membrane is.

• Protein binding is an important consideration influencing drug distribution.

• Many drugs are bound to blood proteins such as serum albumin and are not available as active drugs.

METABOLISM OF DRUG

METABOLISM

METABOLISM

Metabolism of Drug

• Metabolism occurs via two types of reactions:

• Goal: Change the active part of medications (a.k.a functional group) making them more water-soluble and more readily excreted by the kidney.

• Changing the molecular structure of drugs= water solubility= fat solubility= faster excretion of drug in the urine.

and

Metabolism of Drug: Phase I

• Phase I: reactions involve oxidation, hydrolysis, and reduction.

• Oxidation and reduction processes make a molecule's charge more positive or negative than the original drug.

• Regardless of the positivity or negativity, a charged molecule = dissolvable in water

• Take place primarily in the liver by enzymes• Oxidative metabolism may result in formation of

an active metabolite or inactive compound.

Metabolism of Drug: Phase II

• Phase II: reactions involve conjugation to form glucuronides, acetates, or sulfates, by adding glucose, acetate, or sulfate molecules, respectively.

• These reactions generally inactivate the pharmacologic activity of the drug and may make it more prone to elimination by the kidney.

EXCRETION OF DRUG

EXCRETION

Excretion of Drug

• Excretion of a drug = duration of action= toxicity.

• Drugs may be eliminated as a parent drug (unchanged) or as metabolites (changed form).

• PharmacoDYNAMICS: what the drug does to the body; this term refers to the action of the drug at the tissue-,cellular-, and molecular level.

– Specific and different for each drug

PharmacoKINETICS: what the human body does to the drug Excretion occurs primarily through the urine.

Fecal excretion is seen with drugs that are not absorbed from the intestines or have been secreted in the bile.

sweat

KIDNEY

• Most important organ for elimination of drugs and its metabolites

• Eliminated in the urine

① Passive glomerular filtration (most drugs)

② Active tubular secretion (e.g. penicillin)

③ Passive tubular secretion (e.g. salicylates)

• In the case of renal damage:

excretion of drugs; toxicity

BILE

• Usually involve orally ingested unabsorbeddrugs or metabolites excreted in the bile, that are not reabsorbed from the small intestine

• Eliminated through feces

• Examples of drugs

– Phenytoin

– Phenolphthalein

INTESTINES

• Oral and enteral medications (like purgatives) are absorbed in small intestine

• Excreted in large intestine

• Eliminated through stools

• Example:– senna

– cascara

LUNGS

• Drugs like volatile general anaesthetics, ethyl alcohol are excreted through lungs

• Most drugs excreted here are not metabolized first

• Example:– Ketamine

– propofol

SALIVA

• Drugs like iodides and metallic salts are excreted through saliva.

• Such as lead is eliminated through saliva and its deposition produces black lining of teeth.

SWEAT

• Heavy metals like arsenic and mercury are excreted through skin.

BREAST MILK

• Breast milk is more acidic than plasma

• May produce drug toxicity in the nursing infant

• Pulmonary excretion (e.g. breathing) is important as it pertains to the elimination of anesthetic gases and vapors, as well as alcohol.

• Example: pethidine

Video

FACTORS TO CONSIDER WHEN PRESCRIBING DRUGS

FACTORS TO CONSIDER WHEN PRESCRIBING DRUGS

Dosage ofdrugs

Presence ofother drugs

Time of administration

Patientcompliance

Weight ofpatient

Age

Sex

Severity of the disease

Dosage of drugs• Weight of patient

Dose = Adult Dose x Weight (kg)

• Age

Age x Adult dose

70

Age + 12

• Sex

Females are given 7/8 male dose.

• Neonates-new born(calibrated dose)

• Infants-1-6 years(1/4 adults dose)• Children- 6-12 years(1/2 adult

dose)

Presence of other drugs

• Some drugs cancel each other’s effects

• Combined effect would be harmful to the patient

• Hence, consideration must be taken if patient is on other drugs

Time of administration

• Time relationship to meals could influence the actual effective therapeutic dose

• Absorption occurs more rapidly if stomach and upper portion of body are free from food

• Drug action may depreciate when medication given after a meal

• Irritant forms of medication are better tolerated if food already present in gut.

Patient compliance

• Patient does not take medication due to:

o Lack of faith in medication

o Poor understanding of illness

• Patient takes medication incorrectly

• Patient stops taking medication midway

FACTORS THAT MODIFYDRUG EFFECTS

FACTORS THAT MODIFY DRUG EFFECTS

Patient complianceOther drugs

Age & Weight

Rate of elimination

Physiological factors

Tolerence and cross-tolerence

Sex

Pathologic factors

Route of administration

Time of administration

Psychological factors

Genetic variation

0

2

4

6

8

10

8 16 24 32

1st Dose

2nd Dose

3rd Dose

No Effect

Toxic Level

Blo

od

Co

nce

ntr

atio

n

Time

Blood Concentration VS Time Curve of Repeated Dosing

Distribution+

Metabolism

HALF –LIFE/ THERAPEUTIC

LEVEL

CONCLUSION!

1. Pharmacology and it’s use

2. Route of administration

3. Packaging

4. Form of drugs

5. Absorption, Distribution, Metabolism, Excretion of Drugs

THANK YOU FOR LISTENING

NYP DENTAL HYGIENE AND THERAPY 2012