Pharmacy Lecture 8: Routes of Drug Administration 2024-2025 PDF

Pharmacy Bachelor of Pharmacy –PharmD program Fall 2024-2025 Pharmacy Orientation (PIP 111) Lecture 8: The various routes of drug administration Associate Professor : Dr. Sally A. El-Zahaby  Learning outcomes (LO’s) After finishing this lecture , you will acquire the following: 1. Under...

Pharmacy Bachelor of Pharmacy –PharmD program Fall 2024-2025 Pharmacy Orientation (PIP 111) Lecture 8: The various routes of drug administration Associate Professor : Dr. Sally A. El-Zahaby  Learning outcomes (LO’s) After finishing this lecture , you will acquire the following: 1. Understand the different routes of drug administration 2. Specify some advantages and disadvantages for the different routes for administering drugs. 3. Identify the suitable dosage form for each route of drug administration. Associate professor/ Dr. Sally El-Zahaby  Routes of Drug Administration ▪ Local effects are achieved by direct application of the drug to the desired site of action, such as the eye, nose, or skin. ▪ Systemic effects result from the entrance of the drug into the circulatory system and transport to the cellular site of its action. ▪ For systemic effects, a drug may be placed directly in the bloodstream via intravenous injection (IV) or absorbed into the venous circulation following oral or other route of administration. Associate professor/ Dr. Sally El-Zahaby Routes of Drug Administration Term Site Mouth Oral/Peroral (Gastrointestinal tract via mouth) Sublingual Under the tongue Other than the gastrointestinal tract (by injection) Parenteral Intravenous Vein Intra-arterial Artery Intra-articular Joint Subcutaneous Beneath the skin Intramuscular Muscle Dermal/topical Skin surface Intraocular Eye Intranasal Nose Aural Ear Vaginal Vagina Rectal Rectum Intrarespiratory Associate professor/ Dr. Sally El-Zahaby Lung Routes of Drug Administration ▪ An individual drug substance may be formulated into multiple dosage forms that result in different drug absorption rates, times of onset, and duration of action. ▪ E.g. the drug nitroglycerin (used for angina) is formulated in various dosage forms: Sublingual, Buccal, and oral tablets, in addition to ointment & patch. ▪ The sublingual, intravenous, and buccal forms present extremely rapid onsets of action, whereas the oral (swallowed) and topical ointment or patch present slower onsets of action but greater durations of action. ▪ The patch provides the longest duration of action, up to 14 hours following application of a single patch to the skin. ▪ The transdermal nitroglycerin patch allows a single daily dose, whereas the other forms require multiple dosing. Associate professor/ Dr. Sally El-Zahaby Routes of Drug Administration Associate professor/ Dr. Sally El-Zahaby  Route of Administration and the corresponding possible Dosage Forms Route Dosage forms Oral Tablets, Capsules, Solutions, Syrups, Elixirs, Suspensions, Powders Parenteral Solutions, Suspensions Intranasal Solutions, Sprays, Inhalants, Ointments Rectal Ointments, Suppositories, Gels Intra-ocular and intra-aural Solutions, Suspensions Intrarespiratory Aerosols Vaginal Solutions, Ointments, Gels, suppositories Associate professor/ Dr. Sally El-Zahaby Routes of Drug Administration Oral Route of Administration ▪ The oral route is the most frequently used route for drug administration. ▪ Compared with other routes, the oral route is the simplest, most convenient and safest means of drug administration. ▪ Oral dosage forms are usually intended for systemic effects resulting from drug absorption from the GI tract. Associate professor/ Dr. Sally El-Zahaby Routes of Drug Administration Oral Route of Administration ▪ However, some oral suspensions (eg, kaolin) are intended to produce local effects, and these are not absorbed. ▪ Kaolin Oral Suspension is an adsorbent, used as an aid in the treatment of diarrhea. ▪ Kaolin is an adsorptive agent. Kaolin adsorbs water, toxins and bacteria, contributing to firmer stools, reducing fluid loss from diarrhea. Associate professor/ Dr. Sally El-Zahaby Routes of Drug Administration Oral Route of Administration ▪ Disadvantages of the oral route of administration include: 1. The relatively slow onset of action which means slow drug response (compared with parenterally administered drugs) 2. The chance of irregular absorption of drugs, depending upon some factors like the amount or type of food in the gastrointestinal tract; and the destruction of certain drugs by the acid reaction of the stomach (they are called acid-labile drugs) or by gastrointestinal enzymes. Associate professor/ Dr. Sally El-Zahaby Rectal Route ▪ Some drugs are administered rectally for their local effects and others for their systemic effects. ▪ Drugs given rectally may be administered as suppositories, or ointments. ▪ The rectum and the colon can absorb many drugs. ▪ Rectal administration for systemic action may be preferred for the following reasons: 1. Drugs destroyed or inactivated by the environments of the stomach and intestines. 2. When the oral route cannot ne used because of vomiting 3. When the patient is unconscious or incapable of swallowing drugs. ▪ Main disadvantage is poor patient compliance. Associate professor/ Dr. Sally El-Zahaby Parenteral Route ▪ The term parenteral is derived from the Greek words para, meaning outside, and enteron, meaning intestine, which together indicate something done outside of the intestine and not by way of the alimentary tract. ▪ A drug administered parenterally is injected using a fine needle into the body at various sites and to various depths. ▪ The three primary routes of parenteral administration are Subcutaneous, Intramuscular, and Intravenous, although there are others, such as Intracardiac and Intraspinal. Associate professor/ Dr. Sally El-Zahaby Parenteral Route ▪ Advantages of parenteral route: 1. Suitable for drugs destroyed or inactivated in the gastrointestinal tract or drugs too poorly absorbed to provide satisfactory response. 2. The parenteral route is also preferred when rapid absorption is essential, as in emergencies. Absorption by the parenteral route is faster than oral administration. 3. It is useful in treating patients who are unconscious, or unable to accept oral medication. Associate professor/ Dr. Sally El-Zahaby Parenteral Route ▪ Disadvantages of parenteral administration: 1. Once the drug is injected, there is no retreat. That is, once the substance is in the tissues or bloodstream, removal of the drug warranted by toxic effect or an overdose is most difficult. By other means of administration, there is more time between drug administration and drug absorption, which becomes a safety factor by allowing for the extraction of unabsorbed drug (as by the induction of vomiting after an orally administered drug). 2. Also, because of the strict sterility requirements for all injections, they are more expensive than other dosage forms. 3. They require trained personnel for proper administration. 4. Negative patient acceptance of this important route of drug delivery, primarily associated with pain and inconvenience. Note: Sterile means there are no living microorganisms in the end-product. Associate professor/ Dr. Sally El-Zahaby Parenteral Route ▪ Dosage Forms Applicable in case of Parental Route: ▪ Injectable preparations are usually sterile solutions or suspensions of drugs in water or other suitable physiologically acceptable vehicles such as vegetable oil. ▪ Drugs in solution are rapidly absorbed. ▪ A suspension of a drug in a vegetable oil is likely to be much more slowly absorbed than an aqueous solution of the same drug. Associate professor/ Dr. Sally El-Zahaby Parenteral Route ▪ Dosage Forms Applicable in case of Parental Route: ▪ Slow absorption means prolonged drug action, and when this is achieved through pharmaceutical means, the resulting preparation is referred to as a depot. ▪ Since body fluids are aqueous, by use of drugs suspended in oily vehicles, a preparation exhibiting slower absorption characteristics can be formulated to give a depot preparation, providing a reservoir of the drug, which is released slowly into the systemic circulation. ▪ Such preparations are administered by intramuscular injection deep into skeletal muscles. ▪ Example: Depo-Provera is a contraceptive injection that contains the hormone progestin. ▪ Depo-Provera is given as an injection every three months. Associate professor/ Dr. Sally El-Zahaby  Ocular, Otic, and Nasal Routes ▪ Drugs are frequently applied topically to the eye, ear, and mucous membranes of the nose, usually as ointments, suspensions, and solutions. ▪ Ophthalmic solutions and suspensions are sterile aqueous preparations. ▪ Ophthalmic ointments must be sterile and free of grit. Associate professor/ Dr. Sally El-Zahaby Ocular, Otic, and Nasal Routes ▪ Most nasal preparations are solutions or suspensions administered by drops or as a fine mist. ▪ Ear preparations are usually viscid (sticky consistency) so that they have prolonged contact with the affected area. ▪ Ear preparations may be employed simply to soften ear wax, to relieve an earache, or to combat an ear infection. ▪ Eye, ear, and nose preparations usually are not used for systemic effects. ▪ Although ophthalmic and otic preparations are not usually absorbed to any great extent, nasal preparations may be absorbed giving systemic effects after the intranasal application of solution. Associate professor/ Dr. Sally El-Zahaby  Topical route ▪ Drugs are applied topically (i.e. to the skin) mainly for local action in the form of ointments, creams, gels, lotions and pastes ▪ The drugs applied to the skin for local effect include antifungals and anti-inflammatory agents, as well as skin emollients for protective effects. ▪ This route can also be used for systemic drug delivery, in this case it is called transdermal. ▪ Percutaneous absorption is often poor, although several transdermal patches delivering drugs for systemic distribution (e.g. fentanyl patches for severe pain management and nicotine patches for cessation of smoking) are available. Associate professor/ Dr. Sally El-Zahaby  Respiratory route ▪ The lungs provide an excellent surface for absorption when the drug is delivered in gaseous, aerosol mist or ultrafine solid particle form. ▪ For drug particles presented to the lungs as an aerosol, particle size largely determines the extent to which they penetrate the alveolar region, the zone of rapid absorption. ▪ Drug particles that have diameters in the region of 1 μm to 5 μm reach the deep lung. ▪ This delivery route is particularly useful for the direct treatment of asthma, with use of both dry powder aerosols and pressurized metered dose inhalers. Associate professor/ Dr. Sally El-Zahaby Pressurized metered dose inhalers Age Specific Route, Form and Dosage Considerations ▪ Infants (>28 days–12 months): ▪ Use oral syringe or dropper for oral liquid medications ▪ Use the rectus femoris and ventrogluteal muscle sites for intramuscular injections and not the deltoid muscle because this muscle is not yet developed in the infant. ▪ Doses of drugs are based on the infant's weight in kilograms (kg). Oral syringe Associate professor/ Dr. Sally El-Zahaby Age Specific Route, Form and Dosage Considerations ▪ Toddlers (>12 months – 23 months) : ▪ Liquid oral medications are given with a spoon or a cup. ▪ Rectus femoris and ventrogluteal sites are used for intramuscular injections. ▪ Flavors can be used to improve the taste of oral medications, and the dosages continue to be based on kilograms of weight. Associate professor/ Dr. Sally El-Zahaby Age Specific Route, Form and Dosage Considerations ▪ Preschool child (2–5 years) School age child (6–11 years): ▪ These children are usually able to take capsules and tablets. ▪ The deltoid muscle can now be used for intramuscular injections, in addition to the rectus femoris and ventrogluteal intramuscular injection sites. ▪ Dosages continue to be based on kilograms of weight. Associate professor/ Dr. Sally El-Zahaby Age Specific Route, Form and Dosage Considerations ▪ Adolescents: ▪ Adolescents get adult dosages, routes and forms of medications. ▪ The Elderly: ▪ Adult dosages may be decreased because the normal physiological changes of the aging process make this age group more susceptible to side effects, adverse drug reactions, and toxicity and over dosages. ▪ Renal function is decreased which can impair the elimination and clearance of medications, the liver function can be decreased, absorption in the gastrointestinal tract may be decreased. ▪ The initial dose may be as low as ½ of the recommended adult dose. Associate professor/ Dr. Sally El-Zahaby Associate professor/ Dr. Sally El-Zahaby