TOPIC OUTLINE
(1) Pharmacology
(2) Drug
(3) Sources of Drugs
(4) Drug Evaluation
(5) Summary
PHARMACOLOGY
Etymologically, it is the
... [Show More] science of drugs
Greek:
Pharmakos – medicine or drug
Logos – study
It is the study of how chemical agents affect living processes.
It studies the effects of drugs and how they exert their effects to the body
PHARMACOTHERAPEUTICS
Otherwise known as clinical pharmacology, the branch of pharmacology that uses drugs to treat, prevent, and diagnose disease.
Addresses two key concerns:
• The drug’s effects on the body
• The body’s response to the drug.
DRUG
According to who, “any substance or product which is used or intended to be used to modify or explore physiological systems or pathological states for the benefit of the recipient.”
it is a chemical substance used in the treatment, cure, prevention or diagnosis of disease or used to otherwise enhance physical or mental wellbeing.
CHARACTERISTICS OF IDEAL DRUG
(1) it should be biocompatible and biodegradable
(2) no side effects
(3) shows the selectivity in its action
WISH LIST FOR A PERFECT DRUG
(1) Reversible
(2) Predictable
(3) No adverse effects
(4) No interaction
(5) Cheap and simple
GOALS OF PHARMACOLOGY
(1) Maximum benefit for the patient
(2) Minimum harm to the patient
NURSING RESPONSIBILITIES IN DRUG THERAPY
Administering drugs
Assessing drug effects
Intervening to make the drug regimen more tolerable
Providing patient teaching about drugs and the drug regimen
Monitoring the overall patient care plan to prevent medication errors.
SOURCES OF DRUGS
(1) Natural
o Plants
o Animals
o Inorganic compounds
(2) Synthetic
PLANT SOURCES
Is the oldest source of drugs.
Almost all parts of the plants are used i.e leaves, stem, bark, fruits and roots.
PLANT SOURCES
Alkaloids Diverse group of bitter tasting, organic, basic substances found in plants.
EXAMPLES:
Caffeine
Morphine
atropine
Digital Purpurea Sources of digitoxin and digoxin, which are glycosides
Leaves of Eucalyptus Give oil of eucalyptus, which is important component of cough syrup
Tobacco leaves Give nicotine
Poppy Papaver Somniferum Gives morphine (opoid)
ANIMAL SOURCES
Drug obtained from animals sources:
whole animals
glandular products (thyroid organ)
liver extract
polypeptide veoms
non-peptide toxins
ANIMAL SOURCES
Urine of pregnant woman gives hCG used for the treatment of infertility
Thyroif of sheep Source of thyroxin, - used in hypertension
Cod Liver Source of vitamin A and D.
Tobacco leaves Give nicotine
Poppy Papaver Somniferum Gives morphine (opoid)
INORGANIC COMPOUND
Element Therapeutic use
Aluminum Antacid to decrease gastric acidity
Management of hypophosphatemia
Prevention of the formation of phosphate urinary stones
Flurorine
(as fluorid) Prevention of dental cavities
Prevention of osteoporosis
Gold Treatment of rheumatoid arthritis
Iron Treatment of iron deficiency anemia
SYNTHETIC SOURCE
Drugs that are produced upon alteration of chemical compositions of existing plant and animals when proven to have therapeutic activity.
KEY POINTS:
■ Clinical pharmacology is the study of drugs used to treat, diagnose, or prevent a disease.
■ Drugs are chemicals that are introduced into the body and affect the body’s chemical processes.
■ Drugs can come from plants, foods, animals, salts of inorganic compounds, or synthetic sources
DRUG EVALUATION
PRE- CLINICAL TRIALS
In this stage, chemicals that may have therapeutic value are tested on laboratory animals for two main purposes:
To determine whether they have the presumed effects in living tissue.
To evaluate any adverse effects.
At the end of the preclinical trials, some chemicals are discarded for the following reasons:
The chemical lacks therapeutic activity when used with living animals.
The chemical is too toxic to living animals to be worth the risk of developing into a drug.
The chemical is highly teratogenic (causing adverse effects to the fetus).
The safety margins are so small that the chemical would not be useful in the clinical setting.
NOTE:
Some chemicals, however, are found to have therapeutic effects and reasonable safety margins.
This means that the chemicals are therapeutic at doses that are reasonably different from doses that cause toxic effects.
PRE-CLINICAL TRIALS
PHASE 1 STUDIES Uses human volunteers to test the drugs.
More tightly controlled than preclinical trials and are performed by specially trained clinical investigators
The volunteers are fully informed of possible risks and may be paid for their participation.
Usually, the volunteers are healthy, young men.
Women are not good candidates because the chemicals may exert unknown and harmful effects on a woman’s ova
Many chemicals are dropped from the process for the following reasons:
They lack therapeutic effect in humans.
They cause unacceptable adverse effects
They are highly teratogenic.
They are too toxic.
Note:
Some chemicals move to the next stage of testing despite undesirable effects.
For example, the antihypertensive drug minoxidil (Loniten) was found to effectively treat malignant hypertension, but it caused unusual hair growth on the palms and other body areas.
Now, its hair-growing effect has been channeled for therapeutic use into various hair-growth preparations such as Rogaine.
PRE-CLINICAL TRIALS (CON)
PHASE 2 STUDIES Allows clinical investigators to try out the drug in patients who have the disease that the drug is designed to treat to evaluate the drug’s effects.
Usually, phase II studies are performed at various sites across the country—in hospitals, clinics, and doctors’ offices—and are monitored by representatives of the pharmaceutical company studying the drug.
Drug may be removed from further investigation for the following reasons:
It is less effective than anticipated.
It is too toxic when used with patients.
It produces unacceptable adverse effects.
Has a low benefit-to-risk ratio, meaning that the therapeutic benefit it provides does not outweigh the risk of potential adverse effects that it causes.
It is no more effective than other drugs already on the market.
PHASE 3 STUDIES Involves use of the drug in a vast clinical market.
Prescribers are informed of all the known reactions to the drug and precautions required for its safe use.
Prescribers observe patients very closely, monitoring them for any adverse effects.
Prescribers ask patients to keep journals and record any symptoms they experience.
Prescribers then evaluate the reported effects to determine whether they are caused by the disease or by the drug.
A drug that produces unacceptable adverse effects is usually removed from further study by the drug company.
In some cases, the FDA may have to request that a drug be removed from the market.
FDA APPROVAL
Drugs that finish phase III studies are evaluated by the Food and Drug Administration, which relies on committees of experts familiar with the specialty area in which the drugs will be used before marketing in the public.
An approved drug will be given generic name, brand name, and chemical name.
PHASE 4 STUDIES Stage of continual evaluation.
Prescribers are obligated to report to the FDA any untoward or unexpected adverse effects associated with drugs.
Some drugs cause unexpected effects that are not seen until wide distribution occurs.
Sometimes, those effects are therapeutic.
For example:
Patients taking the antiparkinsonism drug amantadine (Symmetrel) were found to have fewer cases of influenza than other patients, leading to the discovery that amantadine is an effective antiviral agent.
In other instances, the unexpected effects are dangerous.
The diet drug dexfenfluramine (Redux) may develop serious heart problems.
NSAID Rofecoxib (Vioxx) show an increase in cardiovascular mortality.
Key points:
■ The FDA carefully regulates the testing and approval of all drugs in this country.
■ To be approved for marketing, a drug must pass through animal testing, testing on healthy humans, selected testing on people with the disease being treated, and then broad testing on people with the disease being treated.
SUMMARY
To be approved for marketing, a drug must pass through:
Animal testing
Testing on healthy humans
Selected testing on people with the disease being treated
Broad testing on people with the disease being treated
TOPIC OUTLINE
(1) Drug classification
(2) Other ways to classify drugs
(3) Drug forms / Preparations
(4) Dosage Formulations Designed to Alter Rate of Release
DRUG CLASSIFICATION
Orphan drug drugs that have been discovered but are not financially viable and therefore have not been “adopted” y any drug company
May be useful in treating a rare disease, or they may have potentially dangerous adverse effects.
these are often abandons after preclinical trials or phase 1 studies
Over-the-counter drugs Products that are available without prescription for self-treatment of a variety of complaints.
OTC drugs have been found to be safe when taken as directed, nurses should consider several problems related to OTC drug use:
- Taking these drugs could mask the signs, and symptoms of underlying disease, making diagnosis difficult.
- Taking these drugs with prescription medication could result in drug interactions and interfere with drug therapy.
- It could result in serious overdoses
Generic drugs These are drugs no longer protected by patent and can be produced by companies other than the one that developed it.
Example:
- Levothyroxine sodium
- L-thyroxines,T4
- Eltroxin, levothroid, synthroid
- Colfosceri palmitate
- Dipalmitoylphosphatidylcholine
- Exosurf neonatal
OTHER WAYS TO CLASSIFY DRUGS
Body system classification answer question:
“Which system of the body is the drug for?”
Example: drugs intended for:
- Cardiovascular system
- Respiratory
- Genitourinary
- Gastrointestinal
- Etc.
Therapeutic use/ clinical indication it answers question:
“what disease or illness is being treated”
Example:
- Diabetes
- Hypertension
- Kidney problems
- Etc.
Physiological / chemical action “ what does the drug do in the body”
Example: drugs to
- Reduce cholesterol
- Lower down blood pressure
- Relieve pain
- Etc.
Prescription / nonprescription “Does the medication require a prescription or can be availed OTC?”
Example:
Prescription drugs:
- Hypertension
- Anti-cancer drugs
Nonprescription drugs:
- Pain relievers
- Supplements
Illegal drugs “Is the drug use for non-therapeutic reasons?”
Example:
Controlled substance:
- Cannabis
DRUGS FORMS/ PREPARATION
1) Solid forms
Tablet / Caplet
a) Chewable tablets
b) Oral disintegrating tablets
c) Enteric – coated tablets
d) Film coated tablets
e) Sugar coated tablets
Capsules
a) Spanules
b) Sprinkle capsules
Powders
Granules
2) Semi solid forms
Emulsions
Ointments
Creams
Lotion
Gels
Pastes
Suppositories
3) Liquid forms
Drops
Solutions
a) Aromatic solution
b) Elixir
c) Syrup
d) Extract
e) Tincture
f) Spirit
g) Irrigating solution
Dispersions
a) Suspension
b) Aqueous suspension
c) Injectable suspension
Enemas
4) Inhalation forms
Aerosols
Sprays
5) Transdermal forms
Patch or disk
Implants
SOLID FORMS
The entire dose is contained in the preparation minimizing measuring errors.
Difficult to swallow, slower onset and ay be degraded by acidic content of the stomach
TYPES OF SOLID FORMS
1 Tablet / caplet
2 Capsules
3 Powder
4 Granules
TABLET / CAPLET
The active ingredient is combined with another substance and pressed into a round or oval solid shape
Soluble or dispersible tablets can safely be dissolved in water
Buccal or sublingual tablets
These are held in the cheek (buccal) or underneath the tongue (sublingual) so the mouth lining absorbs the active ingredient.
FORMS OF TABLET
a.) Chewable tablet Designed to be chewed and contain a base that is flavored or colored.
✔ convenient for patients who have difficulty swallowing tablets
b.) Oral dis integrating tablets (ODT) designed to dissolve in the mouth without water
: Useful for pedia and geriatric clients who have difficulty swallowing and for those who are experiencing nausea and vomiting.
✔ cannot be “checked” by patients who are not compliant with the drug regimen
c.) Enteric – coated tablets With coating to mask the unpleasant flavor or odor, and to protect the drug from the stomach contents.
✔ the coat prevents dissolution in the stomach and are meant to dissolve in the intestines
✔ protects as well the stomach lining with the effects of the drug (i.e KCI and ASA)
d.) Film – coated tablets are coated with a thin outer layer of water soluble material that dissolves rapidly in the stomach
✔ the coat is designed to cover the unpleasant taste or smell and protect sensitive drugs from deterioration due to air and light ( i.e. erythromycin)
e.) Sugar – coated tablets are coated with outside layer of sugar that protects the medication and improves the taste and the appearance of the medication
CAPSULES
The active part of the medicine is contained inside a plastic shell (transparent, semi-transparent, or opaque) that dissolves slowly in the stomach
It contains liquid, powder, granule, or crushed tablet and are formulated with delayed-release characteristics to allow for less-frequent dosing and or side effects
FORMS OF CAPSULES
a.) Spanules capsules that are filled with granules that dissolves at different rates, in effect causing sustained-release of the active ingredient
b.) Sprinkle capsule similar to spanules but unique in that it is designed to be pulled apart and the contents are sprinkled into foods
DOSAGE FORMULATIONS TO DESIGNED TO ALTER RATE RELEASE
1. Immediate-release formulation
✔ the medication is released within a short period of time after the drug is taken
2. Delayed –release formulation
✔ the release of the medication is extended or delayed until it has passed through the stomach
3. Controlled-release formulation
✔ it regulate the rate of release of active ingredient
✔they are designed to vary he dissolution rate release of the active drug
✔ also referred to as long-acting and time-released formulations
4. Sustained-release formulations
✔ it allows the frequency of the dosing to be reduced compared to that of immediate-release dosage forms
5. Extended-release formulations
✔ the active ingredient is released at a constant rate for a prolonged period so that the frequency of dosing is less that the immediate-release dosage form
✔ usually for once daily dosing and the medication is available over an extended period of time
✾compared to immediate-release preparations, advantages of extended-release dosage forms include the following:
✔ Constant drug level following long-term administration
✔ Reduction of side effects
✔ Reduction in administration frequency
✔ increased patient compliance
Lozenges / troches / pastilles
✔ identified as flat, hard, oval, or discoid disks containing a medicinal agent in a suitable flavors base which is held on the mouth to dissolve slowly.
POWDERS
Consist of fine mineral dusts such as talc and are applied by dusting
This is used to absorb moisture from the skin thereby altering conditions favorable to the growth of microorganisms.
It can be used internally and should be dissolved in water prior to ingestion
GRANULES
Larger than powders and are wetted, allowed to dry, and ground into course, irregularly shaped pieces.
More stable than powders and are more suitable in solutions because they will less likely to float in liquids
SEMI SOLID FORMS
They come in tubs, bottles or tubes depending on the type of medicine.
The active part of the medicine is mixed with another substance, making it easy to apply to the skin
These are creams, lotions, or ointments applied directly onto the skin (topical application).
Maybe placed in nasal, vaginal, rectal, and anorectal cavities.
The dosage are too thick not to be considered a liquid form and not solid enough to be considered solid form
Semi solid forms
1 Emulsions
2 Ointments
3 Creams
4 Lotion
5 Gels
6 Pastes
7 Suppositories
EMULSIONS
A type of semi-solid dosage form wherein a mixture is unbendable
✔ One substance is dispersed in the other:
• Oil-in-water (O/W) – emulsion contains small amount of oil dispersed in water
• Water-in-oil (W/O) – emulsion contains small amount of water dispersed in oil
Emulsifying agent
a chemical that is used to bind substances that normally do not mix
it has water-loving and oil-loving properties that keep oil and water together
OINTMENTS
Applied externally to the skin or mucous membranes or can be formulated and sterilized for use in the eyes.
It is an ample of water-in-oil emulsion
It contain medication in a glycol or oil base and can effectively cover the skin
Generally greasier and can leave oily residue at the site of application
CREAMS
It contains suspension or solutions of drug intended for external use.
An example of oil-in-water emulsion and can easily be massaged into the skin without leaving oil residue.
It can be formulated for vaginal or rectal use.
Examples:
Hydrocortisone cream
Benzoyl peroxide cream
Betamethasone valerate cream
LOTIONS
An oil-in-water emulsion that is thinner than a cream because it contains more water
It can penetrate in the skin and can cover large areas without leaving an oily residue
Example:
Calamine lotion
Hydrocortisone lotion
GELS
Contain solid medication like a suspension in a thick liquid that can be used internally or externally
Particles are ultrafine and form semisolid
Can penetrate the skin without leaving residue
Example:
Aluminum hydroxide gel
benzocaine gel
PASTES
It contains more solid materials and less liquid base than a solid
They are like ointments, but stiffer, less greasy, and applied more thickly
Example:
zinc oxide
SUPPOSITORIES
The active part of the medicine is combined with anther substance and pressed in to a “bullet shape”
It can be for local action and vehicle for systematic drugs
Suppositories must not be swallowed
✔ used for children with difficulty taking oral medications
✔rectal suppositories by – pass stomach and helpful to patients with nausea and vomiting
✔ used to treat inflammatory bowel disease or pain
✔ Vaginal suppositories are for yeast infections and vaginal athropy.
Example:
miconazole (vaginal)
bisacodyl (rectal) suppositories
LIQUID FORMS
The active part of the medicine is combined with a liquid to make it easier to take or better absorbed.
It is also called a “mixture”, “solution”, or “syrup”
Types of Liquid forms
1 Drops
2 Solutions
3 Dispersions
4 Enemas
DROPS
These are often used where the active part of the medicine works best if it reaches the affected area directly
✔ tend to be used for eye, ear, or nose
SOLUTIONS
A homogenous mixture of solute and solvent where it is in aqueous (water-based), alcoholic or hydroalchoholic form.
TYPES OF SOLUTION
a.) Aromatic solution Aqueous solution that contains oil or other volatile substance.
usually have pleasant smell
b.) Elixir it is clear, sweet solution that contains dissolved medication in a base of water and ethanol (hydroalchoholic)
c.) Syrup sugar – based solution that may masked the taste of the drug
d.) Extract is a powder or liquid derived from animal or plan sources in which all or most of the solvent has been evaporated
e.) Tincture an alchoholic or hydroalchoholic solution that contains plant extract.
f.) Spirit is an alcoholic or hydroalchoholic solution that contains volatile, aromatic ingredients.
g.) Irrigating solution used for cleansing an area of the body
DISPERSIONS
Medication is not dissolved in a liquid but is “dispersed” throughout.
Suspension:
A mixture of undissolved, fine, solid particles throughout the solid, liquid, or gas.
Aqueous suspension
A mixture of medication in which solids are dispersed in a water medium.
Note:
Suspension needs to be shaken before use and must have “shake well” auxilary label.
Injectable suspension
Allows insoluble drugs to be administered using syringe.
✔often used for depot therapy- the drug is released over a long period of time
Subcutaneous or SC injection
are given just under the surface of the skin
Intramuscular or IM injections
are given into a muscle
Intrathecal injection
given into fluid around the spinal cord
Intravenous or IV
given into vein
ENEMAS
Deliver medications rectally, a way that by-passes the stomach
✔ water-based medication used to evacuate intestinal contents as a preparation for surgeries and examinations of the intestines.
INHALATION FORMS
The active part of the medicine is released under pressure directly into the lungs via the nose or mouth
Types of Inhalation Forms
1 Aerosols
2 Sprays
AEROSOLS
Spray that contains very fine liquid or solid particles in a gas propellant that is packaged under pressure
✔ has a rapid onset of action
SPRAYS
Consists of a container that has a valve assembly unit that contains various bases, such as alcohol or water in pump type dispenser
Emits fine liquid, solid or gaseous material
TRANSDERMAL FORMS
Patch or Dick
Designed to medication to be released in the skin and absorbed into the blood stream
Contains backing, drug reservoir, and control membrane and adhesive layer
Drugs are absorbed slowly, easily applied, and minimized stomach upset
Example: systematic effects
Nitroglycerine
Fentanyl
Scopolamine
Nicotine
NOTES:
Gels are also in transdermal forms which are slowly absorbed in the skin.
IMPLANTS
Placing a drug form or a device in the desired site by insertion in a body tissue or cavity by surgical or appropriate insertion techniques. [Show Less]