LESSON 1

• Another word for medicine is “drug.”
• Drug brings about a change in biologic function through its chemical actions.
• Drug is used to diagnose, cure, treat, or prevent disease
• Medicines come from a variety of sources: Nature, Laboratories, Byproducts of Organisms, Biologically Engineered
• Medicines can be delivered in many ways, such as: swallowed, put into ears or eyes, rubbed onto the skin, injections, inhaled, stuck to skin, under the tongue, inserted into a vein
• There are three dominant methods of classifying the groups by:

  • Mechanism of action - specific biochemical action of drugs
  • Physiologic effect - specific way body responds to a drug
  • Chemical structure
• Pharmacy shelves are filled with medicines that come directly or indirectly from nature,
• Any substance or drug can act either as an agonist or an antagonist.
• Drugs act on a regulator molecule, known as a receptor, which literally receives the agonist or antagonist molecule, and sends the signal to the body system it regulates,
• Agonist - activate
• Antagonist - inhibit
• Thus, drugs that are artificially delivered to patients must have the following characteristics in order to be

  an effective pharmacological drug:

  • very specific size, shape, atomic configuration and electrical charge to be able to interact with the receptor.
  • necessary properties to travel to its site of action or receptor from its site of administration.
  • easily inactivated or excreted from the body once it has been used for its purpose.
• Any drug given to the body can either be a solid, liquid or gas.
• Physical nature of the drug determines how the drug is administered to the body.
• If the drug size is too large, then there is no way for the drug to diffuse into compartments, and the ability to diffuse decreases.
• Small drugs are able to fit through the small pores and into compartments where they can be used.
• 100 Molecular Weight – a drug ideally should not be lower than this
• Drug-receptor bonds are of 3 major types:

  • Covalent (very strong bonds that are not readily broken)
  • Electrostatic (a much more common type of bond)
  • Hydrophobic (These bonds are quite weak.)
• The strength of the drug-receptor bond determines the specificity of the drug.
• Drugs that bond via weak interactions usually are more specific, simply because only one particular type of receptor can be able to bind it and thus induce its effect.
• Another side effect of using a weakly reactive drug is that the drug cannot remain bound for very long, and thus has only short acting effects.
• CHARACTERISTICS OF DRUGS:

  • Physical and Chemical Nature of Drugs
  • Drug Size
  • Drug Reactivity and Drug Bonds
• In 1976, the World Health Organization (WHO) created a multi-dimensional system called the Anatomical Therapeutic Chemical (ATC) Classification System, which categorizes a drug based on five levels.
• Level One: Describes the organ system the drug treats.
• Level Two: Describes the drug's therapeutic effect.
• Level Three: Describes the mechanism/mode of action.
• Level Four: Describes the general chemical properties of the drug.
• Level Five: Describes the chemical components that make up the drug
• Antipyretics: reducing fever (pyrexia/pyresis)
• Analgesics: reducing pain (painkillers)
• Antimalarial drugs: treating malaria
• Antibiotics: inhibiting germ growth.
• Antiseptics: prevention of germ growth.
• Stimulants: stimulates the nervous system
• Tranquilizers: downers
• Prescription-Only Medicine - has to be prescribed by a doctor or other authorized health professional and it has to be dispensed from a pharmacy or from another specifically licensed place;
• Prescription-Only Medicine - virtually all antibiotics and medicines for treating high blood pressure.
• Pharmacy - an intermediate level of control, can be bought only from pharmacies and under a pharmacist’s supervision
• Pharmacy - tablets for emergency contraception and medicines containing codeine for treating pain that is not relieved by aspirin, ibuprofen or paracetamol alone.
• Over-the-counter medicines - covers all general sale medicines and pharmacy medicines. General sale

  medicines are taken for common, easily recognized ailments which usually last around 2–3 days.