Pharmacy Orientation - Third Lecture PDF

Field of Pharmacy Sciences Bachelor of Pharmacy-PharmD (Clinical Pharmacy Program) Pharmacy Orientation & Medical Terminology (PPH101) Lecture: 3 (Pharmacy Orientation Lecture 3) Date: 22 /10 /2024 Dr: Ramy Elsergany, PhD Department of Pha...

Field of Pharmacy Sciences Bachelor of Pharmacy-PharmD (Clinical Pharmacy Program) Pharmacy Orientation & Medical Terminology (PPH101) Lecture: 3 (Pharmacy Orientation Lecture 3) Date: 22 /10 /2024 Dr: Ramy Elsergany, PhD Department of Pharmaceutics & Industrial Pharmacy Lecture overview Routes of drug administration Prodrugs Factors affecting drug dosage 2 Routes of drug administration üOral route üRectal route üParenteral route üTopical route üTransdermal route üRespiratory route üOphthalmic route üSublingual route 3 Oral route Most frequent route for drug administration. Usually intended for systemic effects. Sometimes, for local action in the gastrointestinal tract (GIT) such as antacids. For systemic effect, drug dissolution must occur before drug absorption. Advantages: oCompared with other routes, simple, convenient and safe route. Disadvantages: ØSlow onset of action. ØDestruction and inactivation of drugs by enzymes and HCL in stomach Example: Insulin and Penicillin G are not used orally 4  Oral route Dosage forms taken by oral route: ØTablets ØCapsules ØSolutions ØSuspensions ØElixir (Hydroalcoholic solution) üThe faster the drug dissolution, the faster delivery of API to systemic circulation. üRegarding the onset of action, 5 Solution > suspension > capsule > tablet  Rectal route q Drugs given rectally as: 1. Solids (suppository) 2. Liquids (solutions & emulsions) using enema qUsed mainly for local action rather than systemic effect. Advantages: üUsed when a patient is vomiting or unconscious. üDrugs inactivated or destructed by GIT fluids. Disadvantages: üInconvenient for patient. üVariable systemic drug effect as drug absorption is irregular. 6 Parenteral route Parenteral is derived from 1. para meaning outside 2. enteral meaning intestine Defined as the administration route occurring elsewhere in the body than the mouth and alimentary canal. A hollow needle is injected into the the body at different sites. The three main parenteral routes are: 1. Subcutaneous 2. Intramuscular 3. Intravenous 7  Parenteral route Advantages: ü Faster onset of action üSuitable for emergency situations ü Minimum dose as the absorption step is not required. üBest option for drugs destroyed or inactivated in GIT. Disadvantages: o Painful at the injection site o Non-convenient for children o Requires well-trained person for administration. 8 Parenteral route o Subcutanoeus injection (SC) The drug is injected into the loose subcutaneous tissue. Example: Insulin for diabetic patients o Intramuscular injection (IM) The drug is administered deep into the skeletal muscle. 1. Immediate effect (aqueous solutions) 2. Sustained effect (oily solution and suspensions) oIntravenous injection (IV) üThe drug is injected directly into the vein (systemic circulation). üFaster effect than SC and IM. üAqueous solution is the only dosage form administered by IV route. üAqueous suspension can not be given due to fear of blood embolism (occlusion). 9 * Parenteral drug products should be sterile (free from Micro-organism) to prevent infection. 10  Topical route oDrugs are applied (topically) to the skin for local action (skin disorders). oExamples of pharmaceutical topical formulations: 1. Ointments 2. Creams 3. Pastes 4. Gels oOintments, creams, pastes and gels are semisolid dosage forms. oOintments are hydrophobic or oleaginous in nature whereas creams are hydrophilic (not greasy) in nature. 11 Topical route versus Transdermal route Topical route Transdermal route Applied topically to the skin Applied topically to the skin Local action Systemic action Glycerin cream as skin emollient Nicotine patches for cessation of smoking Nitroglycerin patches for angina Plasters: Adhesive masses applied to the skin to provide prolonged contact at the site, offering protection or mechanical support. 12  Respiratory route oThe lung is an excellent route for drugs due to its high surface area. oDrugs delivered in gaseous and aerosol mist. oDrug particle size determine the extent to which they penetrate the alveolar region. o The smaller the particle size, the deeper they penetrate in the lung. oA successful option for treatment of bronchial asthma. 13  Ophthalmic route oThe ophthalmic route is a subtype of the topical route. o it is used for local action. oOphthalmic dosage forms have to be sterile (free of micro-organism) and isotonic (equal osmotic pressure to that of lacrimal fluids). Advantages: 1. Avoidance of GIT inactivation and destruction 2. Superior local effect versus oral route Disadavatges: 1. Requires frequent administration due to excessive loss. 2. Patient adherence is difficult (only bedtime administration) 14  Sublingual route o A route characterized by placement of dosage form under the tongue o Sublingual area is rich in blood supply and so, greater absorption of drug occurs. Advantages: ü Faster onset of action similar to IV. ü Avoidance of drug destruction in liver (first pass effect) Disadvantages: Ø Suitable only for low-dose drug (potent drugs) Ø Sublingual tablets can be easily broken because of low mechanical strength. 15  Prodrugs o A compound that requires enzymatic biochemical process to produce the active drug. oOlsalazine is a prodrug of 5 aminoslaicylic acid. oThis dimer is more hydrophilic leading to less absorption and reaching the colon for local action. oAzo reductase enzyme in GIT cleaves azo bond resulting in formation of active drug. oProdrugs used for: 1. Modifying absorption 2. Increasing solubility 3. Improving Stability 16  Factors affecting the drug dosage Drug Dose: The lowest amount of drug that is enough to achieve the therapeutic effect without safety problems. Factors: 1. Age üNeonates need dose adjustment as their liver and renal functions are immature. 17  Factors affecting the drug dosage 2. Body weight body weight dose Heavy patients have to take a higher dose than lean patients 3. Body surface area BSA dose Taller patients needs a higher dose than shorter patients 18