Definitions, drug nomenclature, and sources of drugs

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1 Definitions, drug nomenclature, and sources of drugs
1 Definitions, drug nomenclature, and sources of drugs 1.1 DEFINITIONS Pharmacology – Deals with effects of drugs on living system Movement of drug within the body Drug – Any substance or product that is used or intended to be used to modify or explore physiological system or pathological states for the benefit of recipient (WHO) Includes process of absorption (A), distribution (D), metabolism (M), and excretion (E) Pharmacokinetics Means “what the body does to the drug” Study of drugs, their mechanism of action, pharmacological actions, and their adverse effects Pharmacodynamics Means “what drug does to body” Pharmacy Science that deals with preparation, preservation, standardization, compounding, dispensing and proper utilization of drugs Definitions Therapeutics Concerned with treatment of diseases Toxicology Study of poisons, their actions, detection, prevention and treatment of poisoning Chemotherapy Deals with treatment of infectious diseases/cancer Clinical pharmacology Study of drug in man, both healthy volunteers and patients, by comparative clinical trials Satisfy the health care needs of majority of population Essential drugs Should be available at all times, in adequate amounts, and in appropriate dosage forms (WHO) Orphan drug Used for diagnosis, treatment or prevention of rare diseases 2 K395281_C001.indd 2 :45:39 AM

2 1.2 DRUG NOMENCLATURE 1.3 SOURCES OF DRUGS
Definitions, drug nomenclature, and sources of drugs 3 1.2 DRUG NOMENCLATURE e.g. Acetylsalicylic acid Chemical name Not suitable for use in prescription e.g. Aspirin Also called as generic name Non-proprietary name Drug nomenclature Same worldwide Assigned by U.S. Adopted Name (USAN) council e.g. Dispirin Also called brand name Proprietary name Given by pharmaceutical manufacturers A drug may have many brand names 1.3 SOURCES OF DRUGS i. Alkaloids – morphine, atropine, quinine a. Plants ii. Glycosides – digoxin, digitoxin b. Animals Insulin, thyroxine 1. Natural c. Minerals Ferrous sulfate, magnesium sulfate Sources of drugs 2. Synthetic: Aspirin, paracetamol d. Microorganisms Penicillin, streptomycin e. Genetic engineering (recombinant DNAtechnology) Human insulin, hepatitis B vaccine K395281_C001.indd 3 :45:39 AM

3 Patient condition – unconscious, vomiting, diarrhea
2 Routes of drug administration 2.1 FACTORS DETERMINING ROUTES OF DRUG ADMINISTRATION Drug characteristics Type of use – emergency/routin e Patient condition – unconscious, vomiting, diarrhea Factors determining route of administration Age Co-morbid diseases Patient/doctor choice 4 K395281_C002.indd 4 :56:44 AM

4 For allergic or infective conditions of
Routes of drug administration 5 2.2 LOCAL ROUTE One of simplest route Local route Given at site of desired action Minimal side effects Drug applied to skin/mucous membrane for local actions a. Oral cavity e.g. Clotrimazole troche for oral conditions As non-absorbable tablet b. GIT e.g. Neomycin for gut sterilization before surgery Liquid drug is administered in rectum As evacuant enema for bowel evacuation e.g. Soap water enema; soap acts as lubricant and water stimulates the rectum c. Rectum and anal canal 1. Topical Retention enema e.g. Methylpredinisolone in ulcerative colitis Suppository Solid dosage form drug is inserted in rectum e.g. Bisacodyl for bowel evacuation As drops, ointments, sprays, etc. d. Eye, ear, and nose For allergic or infective conditions of eye, ear, and nose e. Bronchi As inhalation e.g. Salbutamol inhalation for bronchial asthma, and COPD (chronic obstructive pulmonary disease) f. Vagina As tablet, cream, pessary For vaginal candidiasis g. Urethra As jelly e.g. Lignocaine 2. Deeper areas are reached by using syringe and needle e.g. Infiltration of local anesthesia K395281_C002.indd 5 :56:44 AM

5 2.3 SYSTEMIC ROUTE (Continued)
6 Pharmacology mind maps for medical students and allied health professionals 2.3 SYSTEMIC ROUTE Systemic route Drug reaches blood and produces systemic effects i.e. Enteral route Oral, sublingual, and rectal route Most common and accepted e.g. Tablets, capsules, syrups, etc. Safe Cheap Advantages Painless Convenient for repeat and long-term use Self-administered Slow onset, not used in emergency Unpalatable, highly irritant drugs cannot be given Unabsorbable drugs cannot be given (e.g. neomycin) 1. Oral route Disadvantages Drugs destroyed by digestive juices cannot be given (e.g. insulin) Drugs with high first-pass metabolism cannot be given (e.g. lignocaine) Cannot be given in unconscious/ uncooperative/unreliable patients Cannot be given in patients with vomiting or diarrhea Prevents gastric irritation Protects drug from gastric acid Retards drug absorption and  its duration of action Done by cellulose, acetate, etc. Sustained/controlled release formulation Enteric-coating of tablets Consists of different coatings dissolving at different time intervals  Duration of action  Dosing frequency  Patient compliance e.g. Sustained-release nifedipine (Continued) :56:45 AM

6 Action can be terminated by spitting out drug
Routes of drug administration 7 2.3 SYSTEMIC ROUTE (Continued) Drug is kept under tongue Absorbed through the buccal mucosa Enters systemic circulation Bypasses first-pass liver metabolism Rapid onset e.g. Nitroglycerin, buprenorphine Action can be terminated by spitting out drug 2. Sublingual route Advantages Bypasses first-pass liver metabolism Self-administration is possible Irritant and lipid- insoluble drugs cannot be given Unpalatable drugs with bad smell cannot be given Disadvantages Cannot be used in children i.e. Retention enema e.g. Methylprednisolone For local effect Evacuant enema e.g. Soapy water 3. Rectal route Solids and liquid dosage forms used i. Enema For systemic effect e.g. Diazepam for febrile convulsions in children (Continued) :56:45 AM

7 2.3 SYSTEMIC ROUTE (Continued)
8 Pharmacology mind maps for medical students and allied health professionals 2.3 SYSTEMIC ROUTE (Continued) Administered other than enteral route Injection, inhalation, and transdermal route Rapid onset, and can be used in emergency Also be used in unconscious/unco- operative/unreliable patients Used in presence of vomiting and diarrhea Advantages Suitable for irritant drugs B. Parenteral route Drugs with high first-pass metabolism can be given by this route Drugs that are not absorbed orally also can be given Drugs destroyed by digestive juices can be administerd by this route Require sterilization and aseptic conditions Invasive technique, painful Disadvantages Can cause local tissue injury; e.g. nerves, vessels, etc. Requires technical experts, hence cannot be self-administered Expensive (Continued) :56:45 AM

8 circulation for systemic effects
Routes of drug administration 9 2.3 SYSTEMIC ROUTE (Continued) Volatile liquids and gases are administered by this route e.g. General anesthetics Rapid onset 1. Inhalation Advantages Lower dose is required, fewer systemic side effects Dose regulation is possible Disadvantages Local irritation can cause T respiratory secretions and bronchospasm Scopolamine for motion sickness Patches deliver drug into circulation for systemic effects Nitroglycerin for angina e.g. Estrogen for hormone replacement therapy (HRT) Fentanyl for analgesia Self-administered Good patient compliance 2. Transdermal route (adhesive patches) Advantages Prolonged action Minimal side effects Constant plasma concentration Expensive Disadvantages Local irritation (itching, dermatitis) Patch may fall off without being noticed (Continued) :56:45 AM

9 2.3 SYSTEMIC ROUTE (Continued)
10 Pharmacology mind maps for medical students and allied health professionals 2.3 SYSTEMIC ROUTE (Continued) a. Intradermal Injected into dermal layer of skin e.g. BCG vaccination, drug sensitivity testing Injected into subcutaneous tissue e.g. Insulin, adrenaline Self-administered; e.g. insulin Advantages Depot preparations can be used; e.g. norplant for contraception b. Subcutaneous Disadvantages 3. Injection Unsuitable for irritant drugs Slow onset, unsuitable for emergency Injected into large muscles Deltoid, gluteus maximum, lateral aspect of thigh in children Rapid onset compared to oral route Advantages Depot preparations (used to prolong drug action), mild irritants, soluble substances and suspensions can be given c. Intramuscular Requires aseptic condition Painful, may lead to abscess Disadvantages Self-administration is not possible Local tissue injury can occur; e.g. nerves (Continued) :56:45 AM

10 2.3 SYSTEMIC ROUTE (Continued)
Routes of drug administration 11 2.3 SYSTEMIC ROUTE (Continued) Bolus administration – single, large dose rapidly/slowly injected as single unit e.g. Furosemide Direct injection of drug into vein Slow IV injection e.g. Morphine IV infusion – addition of drug into a bottle containing dextrose/saline e.g. Dopamine infusion in cardiogenic shock 100% bioavailability Rapid onset, suitable for emergencies Large volume of fluid can be given (IV dextrose) Advantages Highly irritant drugs can be given (e.g. anticancer drugs) Hypertonic solutions can be given (20% mannitol) Constant plasma levels can be maintained (dopamine in cardiogenic shock) d. Intravenous Once drug is injected, drugs action cannot be stopped Local irritation, thrombophlebitis Strict aseptic conditions are mandatory Disadvantages Self-administration is not possible Drug extravasation cause necrosis, slougting Depot preparations cannot be given Administer drugs slowly, otherwise toxicity Caution Ensure tip of needle is in vein (Continued) :56:46 AM

11 2.3 SYSTEMIC ROUTE (Continued)
12 Pharmacology mind maps for medical students and allied health professionals 2.3 SYSTEMIC ROUTE (Continued) Rarely used now e. Intra-arterial Used diagnostically e.g. Coronary angiography Sometimes anticancer drugs can be given f. Intra-thecal Injection of drug in subarachnoid space e.g. Spinal anesthesia (lignocaine), antibiotics (in meningitis) Direct injection of drug into joint space e.g. Hydrocortisone for rheumatoid arthritis g. Intra-articular Requires strict aseptic condition Repeated use can damage cartilage 2.4 SPECIALIZED DRUG DELIVERY Kept beneath lower eyelid e.g. Pilocarpine in glaucoma 1. Ocusert Single application releases drug for 1 wk Intrauterine contraceptive device 2. Progestasert C. Specialized drug delivery Releases progesterone for 1 yr 3. Liposomes Drug incorporated in minute phospholipid vesicles e.g. Liposomal amphotericin for fungal infection Immunoglobulins react with specific antigen 4. Monoclonal antibiotics Used for targeted delivery e.g. Anticancer drugs :56:46 AM