Pharmacology: Drug Classifications and Mechanisms

• INP Exam-Focus Revision Slides is for Semester Oct 2024 and Feb 2025 exams

Test Details

• The test is on Thursday, 20 Feb 2025
• Reporting time is 2.30pm, with the test taking place from 3-5pm
• Refer to NPAL for location and seat number
• The exam type is pen and paper
• Items to bring: Student ID, Calculator, Pens, Pencil 2B, Eraser and Ruler

Content Division - Term 1

• Drug Source, Naming of Drugs, Generic and Proprietary drugs, Forensic Classification, POM & OTC drugs is covered in slides 1-35
• Abbreviations are covered in slides 36-48
• Routes of Drug Administration and advantages and disadvantages of each route are covered in slides 49-71
• Calculations and Fluid Scheduling is covered in slides 72-89
• Medication Error is covered in slides 90-104
• Pharmacokinetics are covered in slides 105-133

Content Division - Term 2

• Pharmacodynamics-Mechanism of Action of Drugs, Agonist and Antagonist are covered in slides 134-146
• Therapeutic Index is covered in slides 147-154
• Potency and Efficacy are covered in slides 155-156
• Drug-drug, drug-food Interactions are covered in slides 157-168
• Autonomic Nervous System Drugs are covered in slides 169-193

Definition

• Pharmacology is the study of medicines
• Drugs = Medications
• Therapeutics is the branch of medicine concerned with disease prevention and treatment of suffering
• Pharmacotherapy is applying drugs for disease prevention and treatment of suffering
• Therapeutic effects are the desired action of drugs
• Adverse effects are the undesired outcome of drugs

Sources of Drugs

• Drugs are derived from Plants (e.g. herbal remedies, digitalis & opium-based drugs)
• Drugs are derived from Animals (e.g. Insulin or growth hormone from pigs and cows, recombinant DNA)
• Drugs are derived from Inorganic compounds (e.g aluminum [antacid], fluoride [dental caries], gold [RA], iron [Iron deficiency anemia])
• Drugs are derived from Synthetic sources [e.g. barbiturates (CNS depressant), sulfonamides (antibacterial), and aspirin]
• Synthetic sources are NOT natural
• Most modern medicines are produced synthetically

Singapore Drug Classification

• Registered medicinal drugs are classified into 3 categories:
• Prescription Only Medicine (POM)
• Pharmacy only medicine (P)
• General Sale List medicine (GSL)
• Pharmacy only medicine (P) and General Sale List medicine (GSL) are Over the counter (OTC)
• Forensic Classification' categorizes medicines into 3 groups based on risk profile, experience with the product, public health considerations, and the seriousness of the medical condition

Prescription Only Medicine (POM)

• To obtain POM an order must authorize a patient to receive a drug
• The patient order must be in the form of a prescription
• All prescriptions must be signed and dated by the doctor
• Prescription must me written by a doctor (electronic records are acceptable)
• The patient's name and address, and doctor's name must be included
• The dose, quantity, number or intervals must be listed
• Cannot be written in code, must be written in full including the amount

Controlled Drugs

• Controlled drugs refer to Special group of drugs that are:
  • Highly addictive
  • Misused/ abused
  • May be used to cause harm
• In addition, the prescriptions for controlled drugs must indicate
  • The dosage form, the strength of the preparation
  • The total quantity or dosage units to be dispensed
  • All must be written in both words and numbers
• A tablet Morphine example would read: "Tablet Morphine 5 (five) mg, to take 1 (one) OM x 5 (five) days Total tablets= 5 (five) tablets."

Over-The-Counter Drugs (OTC)

• OTC drugs Include Pharmacy medicines (P) and General Sales List (GSL)
• OTC drugs do not require a doctor's prescription
• These medicines generally have a high safety margin
• Consumers should diagnose the medical condition and monitor the effectiveness of treatment
• OTC Safety profiles must have adherence to guidelines, a limited drug interaction profile, a low potential for abuse, and are easy to use and monitor

Advantages and Disadvantages: POM

• Advantages of Prescription Only Medicines (POM) are:
  • Opportunity for physician to examine patient, Proper diagnosis and treatment plan, Practitioners can maximize therapy, patient education on use and adverse effects
• Disadvantages of Prescription Drugs are:
  • Difficulty in obtaining a continuous supply, Costs are higher, Time needed to visit Dr. or make clinic appointments

Advantages and Disadvantages: OTC

• Advantages of OTC
  • Patients can self-treat minor ailments, decreasing physician and pharmacists dispensing thus costs reduces and Increasing patient's responsibility of his own health, patients are able to obtain a continuous supply of medication
• Disadvantages of OTC
  • Where patient does not follow the written leaflet instructions, OTC drugs can have serious adverse such as liver damage, and create a Delay in seeking proper medical care Increase “out of pocket” costs if complications arise, and a Deficient knowledge in use of medication creates possible harm
  • Other effects include: drug-food, drug-herb interactions and increased disease progression, worsening body function, and possibly ineffectively treatment.

Naming Of drugs

• Drugs have three names: Chemical name, Generic name, and Brand name
• Chemical Name is assigned using standard nomenclature established by the International Union of Pure and Applied Chemistry (IUPAC)
• Drugs can be named and classified by some of the chemical structure, known as the chemical group name.
• The Generic Name is assigned by the U.S. Adopted Name Council (USAN)
• There is only one generic name for each drug in one country.
  • US generic name for Paracetamol differs from UK where it calls it= acetaminophen
• Generic names can provide info on the pharmacological drug class
  • Beta-blockers end with "-lol", HMG-CoA reductase inhibitors end with "-statin", Penicillins end with "-cillin"
• Brand Name is also called proprietary, product, or trade name.
  • The pharmaceutical company assigns the brand name that are usually short, catchy and easy to remember, where one drug class may have many trade names and only one generic name.

Proprietary vs Generics Drugs

• The company that develops a drug gives it a brand name
  • The first company producing a unique drug receives 15–20 years of patent rights upon approval.
  • Patent rights are exclusive rights granted to companies to recoup development costs.
• After that, other companies can create similar/generic versions as substitutes
  • In Singapore, the substitute can be used if the prescription is written with the generic name with approval otherwise having to be sort
• Generic drugs have identical active (chemical) doses, but their formulations or inert (inactive) ingredients may differ
  • Those inactive ingredients include preservatives, coloring agents, or flavoring agents.
  • They can change bioavailability of the drug.
• Active ingredients have primary role of the acting as therapeutic effect

Differences between proprietary and generic drugs

• Brand/proprietary drugs have a higher cost, usually no insurance coverage or subsidies, Similar testing that is approved, and have strength and appearance differences.
• Generic drugs have a lower cost, full insurance coverage, similarly testing that is approved and can have differences in inactive ingredients. Bioavailability difference could apply between trade and generics

Drugs for Critical Care

• Bioavailability differences could be important, with with drugs given for critical care (e.g. ICU Drugs) and those with a narrow safety margin.
  • Generics are usually not used in these situations
• However, the generic equivalent may be safely substituted for most treatment cases.
• Drugs are divided into different groups by Therapeutic and Pharmacologic Classification
• Therapeutic Classification organizes drugs based on their therapeutic usefulness in treating a particular disease.
• Pharmacologic Classification organizes drugs according to the way they act.
• grouping of drugs based on their therapeutic use/specific condition treatment, the therapeutic classification helps healthcare providers to be well informed in the terms of patient care.
• Pharmacological classification focuses on the how or the process drugs work at a cellular level

Abbreviations For medication usage

• Abbreviations serve both the time and interval of the administration
  • o.d., od, OD, which mean “omne in die” mean 1x a day and alternate in variety for timing too q.d., qd, which mean “ quague die“ is every day

Common Abbreviation

• q.a.m., qAM, qam , quaque ante meridiem is every morning
• Common eye and ear drop abbreviations:
  • a/A = ear
  • o/O = eye
• Both of your eyes Both: u, son with U and the other: U, but a difference between Right and Left:
  • left Is S, right Is D, so you can see: Right: d
• Others include:
  • ii/i = 2
  • iii/iii = 3 tabs (2 tabs)

Abbreviation By Dosage

• Tablet : cap
• Injection : inj
• Pessary : pess
• Suppository : supp
• Patient control Analgesia : PCA

Duration Abbreviation

• One of 7 Days : 1/7
• One of 52 Weeks = 1/52

Route of Administration

• IM, can mean intravenous or intramuscular
• Pv means Per Vagina or Pessary
• Iv best bioavailability
• Po oral, is poorest

Definition Of Route AAdministration

• A means to have certain interactions to a body
• the kind of method to take to administer to the body

Route Of Administration

• Route of Administration has 3 Big groups to administer the body

First Pass Effect

• This occurs when a drug is absorbed from the gastrointestinal tract, or any oral absorbed substance passes, passes through the liver before reaching the rest of the body. Once that that happen, that affects the bioavailability greatly, thus changing the drug
• Sublingual or Suppository can work and bypass some effect

Parenteral Route

• The desire to deliver the drug directly, as if on direct, to the bloodstream
• Can be thought of as intramuscular, intravenous, subcutaneous, etc

Intradermal Vs Intramuscular

• Intramuscular is the most common area for shots, whereas intradermal shots are rare and for test cases
• Topical Routes
• Topical routes is applying medication, externally as if right to the skin, there is some exceptions that can bypass the skin.
• They may or may not produce Systemic effects

Different Types of topical

• Otic = into the ear
• Conjunctiva, or ocular, is the eye

Advantages And Disadvantages Of Intravenous

• ADVANTAGES: -- The drug is quick to interact when injected, thus making as a Quick response as possible -- All drugs will be absorbed in the body Bioavailability is 100 Percents the chemical that being applied directly.
• DISADVANTAGES: -- Finding a vein may be difficult or finding easy access to the drug -- can be toxic, if there a quick response -- requires a trained personnel only

Caluclation

• Weight is one key essential
• Unit must be the same or a different

The Rights Principles

• Is following 6 steps
• the right action
• the documentation

The Three Steps

• To prevent and error, one has to prevent and ensure for 3 steps —checking with IMR, and the drug was remove with the cupboard .
• To be ensure what being poured out , what the amount. And the third and final is what before the administration.

Medication Error

• The main goal is to prevent it

• One of action is to check the the doctor order sheet, checking of transcribing of any errors or the same as as it can

• The report has to be 100 accuracy as it can be

• Important to do check up and do the full amount of checking from the patient, so that safety will still remain as priority action. —What an impact does these steps for does it harm. And is it also important for that, who does it actually affect.

• What’s key in an aspect of it it’s that if there client safety with the steps?

• The pharmacokinetics is basically what the body goes through with what is absorbs, there 4 principle components of it with absorption, Distribution, metabolism and excretion

• First process of pharmacokinetics is “absorption” the process of the drug side being administered.

• Bio availability is “what is exactly given to the patient.

Affecting factors of a Body

• Is it the route. Or is it the high of dosage.
• Size of drug molecule, flow of blood ,ionization of drug.

The different route for the body

• Blood flow to the body is the key to distribution
• Physical distribution does have a factor.

The two barrier

• The fetal barrier as it to a physical barrier that separates to both side of the fetus and the Mother side
• Main process of drug is metabolism. This key to how drugs by being more soluble. Thus making them excrtre in the body. All of microsomes. It converts

Pharmadynamics

• Is to know the side effect and why it exists
• It can can agonist and antagonism with either the effect and the cause of the drug.

Effects

• To know the effects of the cell through the drugs. As it’s affect the body when injected with the drug.

• Can be reversible and reversible through chemical action. It all matter through cell level

• The action is affected also in to with the drug, thus the receptor action is different to be affect.

Factor Of Affect

• Varying of metabolism
• Age

Key of excretion

• Reabsorption
• Filtration
• Tubule
• As the elderly had there drug metabolism, they have are giving lower because of this .

Body reaction

• Nervous system is the key reaction in all conditions.

Neurotransmitter system

• Is a site of contact where one communication is through receptor.

ANS

• Has with all other chemical reaction, that the body is taking. Such is heart beating.
• Two division —Sympathetic nerve —parasympathetic nerve

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