Describe the relationship between dosage forms and routes of administration.
A medication administration route is often classified by the location at which the drug is applied, such as oral or intravenous. The choice of routes in which the medications are applied depends not only on convenience but also on the drug’s properties and pharmacokinetics. This activity describes medication administration routes and explains the interprofessional team's role in improving care for patients who undergo medication administration. Show Objectives:
IntroductionA medication administration route is often classified by the location at which the drug is administered, such as oral or intravenous. The choice of routes in which the medication is given depends not only on convenience and compliance but also on the drug’s pharmacokinetics and pharmacodynamic profile. Therefore it is crucial to understand the characteristics of the various routes and techniques associated with them. Many interprofessional healthcare team members are involved in the administration of medications to patients. Anatomy and PhysiologyEnteral Route of Medication
Parenteral Route of Medication
Other Routes of Medication
IndicationsEnteral Routes of Medication [9] 1. Oral This is convenient and is indicated for patients who can ingest and tolerate an oral form of medication. Some medications with short half-lives are administered orally as timed-release or sustained-release forms that get absorbed over several hours. Advantages:
Disadvantages:
2. Sublingual and Buccal Routes These are indicated for medications with high first-pass metabolism that need to avoid clearance by the liver. For instance, nitroglycerin is cleared more than 90% during a single pass through the liver; therefore, it is given in a sublingual form. Advantages:
Disadvantages:
3. Rectal Route This route is useful for patients with gastrointestinal motility problems such as dysphagia or ileus that can interfere with delivering the drug to the intestinal tract. The rectal route is also often utilized in patients near the end of life undergoing hospice care.[10] Advantages:
Disadvantages:
Parenteral Routes of Medication [9] 1. Intravenous Route This directly administers the medications to the systemic circulation. It is indicated when a rapid drug effect is desired, a precise serum drug level is needed, or when drugs are unstable or poorly absorbed in the gastrointestinal tract. It is also the route utilized in patients with altered mental status or severe nausea or vomiting, unable to tolerate oral medications. Advantages:
Disadvantages:
2. Intramuscular Route[11] This can be utilized when oral drug absorption occurs in an erratic or incomplete pattern; the drug has high first-pass metabolism or when the patient is not compliant. A depot preparation of the drug can be given intramuscularly, and the medication dissolves slowly into the circulation to provide a sustained dose over a more extended time. An example includes haloperidol decanoate. Vaccines are also administered via the intramuscular route.[12] Disadvantages:
3. Subcutaneous Route This is used when the drug's molecular size is too large to be effectively absorbed in the intestinal tract or when better bioavailability or a faster absorption rate is needed than the oral route. It is easy to administer and requires minimal skills, so patients can often self-administer the medication. Common medications administered subcutaneously include insulin, heparin, and monoclonal antibodies. The rate of absorption of drugs through this route can be enhanced by infiltration with the enzyme hyaluronidase. The major factors that affect the rate of absorption by this route include size of the molecules (large molecules having slow penetration), viscosity, and the anatomical characteristics of the site of injection (vascularity and amount of fatty tissue). Disadvantages:
Other Routes of Medication [9] 1. Intranasal Route This can be utilized in administering nasal decongestants for cold or allergy treatment. Other uses include desmopressin for the treatment of diabetes insipidus or intranasal calcitonin for the treatment of osteoporosis. Factors that affect the rate of absorption of drugs via the nasal route are:
Enhancement of nasal drug delivery: Rapid mucociliary clearance can lead to poor bioavailability of the drug. This can be overcome by in situ gelling drug delivery. Chitosan is a natural bioadhesive polysaccharide obtained from crustacean shells that can be used as an absorption enhancer. Chitosan binds to the nasal mucosal membrane and facilitates drug absorption through paracellular transport and other mechanisms. Advantages:
Disadvantages:
2. Inhalational Route The alveolar epithelium is approximately 100 square meters in adults and the alveolar volume is 4000–6000 mL when compared to the airway volume of 400 ml. This provides a greater surface area for absorption of the inhaled substances. An inhaled medication route can be utilized to administer albuterol or corticosteroids such as fluticasone and to deliver inhaled anesthetics to patients. Barriers to the absorption of substances in the alveoli are surfactants, surface lining fluid including the mucus, the epithelial membrane, extravascular space, and vascular endothelium. The absorption of macromolecules by the lungs is considered to be by transcytosis (not significant for macromolecules >40 kDa), paracellular absorption, and drug transporter proteins. Advantages:
Disadvantages:
3. Vaginal Route This is not commonly used but can deliver low, continuous dosing of medications which can help achieve stable drug levels. A variety of formulations can be given vaginally, including tablets, creams, gels, ointments, and pessaries. Common medications given via the vaginal route include vaginal estrogen therapy for urogenital atrophy, contraceptive rings, antibiotics, or antifungals.[13] 4. Transdermal Route Iontophoresis and microneedles are playing an increasing role in transdermal drug delivery. A technique has been described using hydrogel-forming microneedle arrays in combination with electro-phoresis for controlled transdermal delivery of biomacromolecules in a simple, one-step approach. Drug Delivery to the Cardiovascular System Methods for local administration of drugs to the cardiovascular system are:
Drug Delivery to the Central Nervous System (CNS) The blood-brain barrier is a major obstruction to the delivery of drugs into the central nervous system. Some methods to reduce the obstruction by this barrier include:
ContraindicationsEach medication administration route has unique contraindications, and the healthcare team members need to recognize them. An oral medication route is contraindicated for patients who cannot tolerate oral drugs, such as those who have altered mental status or have nausea or vomiting that hinder them from safely ingesting the drug orally. A rectal route is contraindicated in patients with active rectal bleeding or diarrhea or after a recent rectal or bowel surgery. An intramuscular route is contraindicated in an active infection or inflammation at the site of drug administration, myopathies, muscular atrophy, thrombocytopenia, or coagulopathy. A subcutaneous route of medication is contraindicated in an actively infectious or inflamed site. Doses that require to be injected more than 1.5 mL at once should be avoided. Subcutaneous injection volumes larger than 2 mL are associated with adverse effects, including pain and leakage at the injection site.[16] An intranasal medication is contraindicated in patients with nasal trauma, anatomic obstruction, the presence of a foreign body, or copious mucous or bleeding. Similarly, an inhaled medication is contraindicated in patients with airflow obstruction. EquipmentThe equipment required depends on the route chosen for medication administration. In general, equipment needed for the parenteral route may include gauze, dry cotton swab, nitrile gloves, chlorhexidine or alcohol-based antiseptic agent, tourniquet, appropriately gauged intravenous catheter, syringe, normal saline flush, and a bandage. A local anesthetic agent may be used for larger cannulas or to minimize discomfort in some patients, such as pediatric patients. A lubricant can be utilized in the rectal or vaginal administration of medication to reduce friction and discomfort. PersonnelOne personnel is usually sufficient for all routes of medication administration. Still, additional assistance may be helpful if the patient is unable to stay in an optimal position or when administering to children. PreparationThe “five rights” are emphasized for the preparation of medication administration: right patient, right drug, right dose, right site, and right timing.[17] It is essential to explain to patients how the medication will be administered, obtain consent for procedures when indicated (e.g., central venous catheter), and help prepare patients before they receive their medication. The site of application of the medication should be chosen based on its adequacy and indications. The label on the medication should be checked for its name, dose, and approved usage route. TechniqueTechniques involved in each route of medication administration are different, and some of the important points are summarized as follows: Intravenous Route A tourniquet may be used over the site intended for the intravenous medication to make the vein more visible and easier to access. However, when used, the tourniquet must be removed before injecting the medication to prevent extravasation. In central lines or peripherally inserted central catheter (PICC) lines for medication administration, ultrasound guidance is often used.[18] Intramuscular Route Intramuscular injection should be done at a perpendicular angle as it has been shown to be the most effective method for patient comfort, safety, and medication efficacy.[19] Skin traction and deep pressure on the muscle can help decrease patients' pain and discomfort.[20] When injecting to the dorsogluteal site, aspirating for a few seconds is recommended, given its proximity to the gluteal artery.[21] Subcutaneous Route A subcutaneous route requires minimal skills and training, and patients can often quickly learn to inject medications into themselves. It is recommended that instead of using the same site, patients rotate the sites of injection to avoid complications such as lipohypertrophy that can cause incomplete medication absorption.[22] The injection is usually at an angle if using a needle/syringe or at a perpendicular angle if using an injector pen. Rectal Route It is recommended to have the patient lie on the left side with the right knee bent towards the chest as this position enables the medication to flow into the rectum and subsequently to the sigmoid colon by gravity. Separate the buttocks with the non-dominant gloved hand and gently insert the medicine 2 to 4 cm into the rectum using the dominant hand's gloved index finger. A lubricant may be used for the patient’s comfort. If administering a laxative suppository, the patient will need a bedpan or commode or be placed close to the toilet. It is recommended that the patient remains on the side for 5 to 10 minutes unless otherwise specified by the medication’s directions.[23] Vaginal Route Position the patient onto their back with legs bent and feet resting flat on the bed. A lubricant can be used to reduce friction against the vaginal mucosa as the medication is administered. Gently separate labial folds with the non-dominant gloved hand while with the dominant gloved index finger, insert the lubricated suppository to about 8-10 cm along the posterior vaginal wall. Inhaled Route Each inhaler has instructions from the manufacturer. For metered-dose inhalers, some of the essential techniques include: shaking the inhaler vigorously for a few seconds before each puff; inhaling through the mouth, not the nose when breathing in the medication; keeping the tongue under the mouthpiece to avoid blocking the mouthpiece; taking a slow deep breath as the medication canister is pressed and holding the breath for 5 to 10 seconds and then exhaling. Cleaning the inhaler regularly is recommended to prevent a buildup of medications. Spacers or chambers can help patients inhale the aerosol and help decrease the deposition of the medication in the mouth or throat. ComplicationsThe medical personnel should recognize the potential complications of each route of medication administration. The parenteral route can cause pain or discomfort in the area of application, bleeding, bruising, infection, or inflammation. Infiltration is a common complication of the intravenous route whereby the intravenous fluid or medication enters the surrounding tissue and not the vein. It is not deemed severe unless the infiltrated medication is a compound that may damage the surrounding tissue, such as a chemotherapeutic agent or a vesicant, in which case the complication is termed extravasation, and this may lead to tissue necrosis. Although the intravenous route has the benefit of rapidly delivering drugs to patients, this may cause nonspecific severe cardiopulmonary effects, and healthcare personnel should closely monitor the patients. For intramuscular injections, there are site-specific complications to be aware of. In deltoid muscle injection, an unintentional injury to radial and axillary nerves with resultant paralysis or neuropathy may not always resolve.[24] As discussed previously, the dorsogluteal site injection carries an increased risk of sciatic nerve injury, and therefore the ventrogluteal site is more recommended.[3] Complications associated with the subcutaneous route are more medication-specific. For instance, in subcutaneous insulin, lipohypertrophy or lipoatrophy can develop, leading to slower or incomplete insulin absorption at the injection site.[25] Therefore, using different injection sites is recommended for patients. In the intranasal route, interseptal nasal perforation had been reported in some patients, particularly those using intranasal steroids for a prolonged period.[26] Rebound congestion in patients on chronic nasal decongestants is seen as the sinusoid vasculatures do not respond as well to the adrenergic drug with prolonged use and result in a hyperemic, congested mucosa. Complications associated with inhaled medications are also often medication-specific. For instance, inhaled corticosteroids can cause local deposition that leads to thrush or dysphonia, and sometimes cough, throat irritation, and contact hypersensitivity also have been reported.[27] Clinical SignificanceAdministering medication is the hallmark of treating patients in different healthcare settings. The interprofessional healthcare team members need to understand the unique properties of each route of medication administration. Knowing contraindications and potential complications can help avoid unnecessary risks in patients, while understanding indications can help choose the best medication delivery route. Enhancing Healthcare Team OutcomesEach route of medication administration has its unique characteristics that need to be considered by the healthcare team when caring for patients. Specific techniques, such as central venous catheter placement and PICC lines, require more advanced skills and training, and it is important to communicate and plan how the process will proceed. The healthcare members involved in patient care should also be aware of and actively monitor for potential immediate and delayed medication administration complications. Informing patients well about the process and involving them in the decision-making process whenever appropriate can improve the overall healthcare outcome. For instance, in the rectal or vaginal route, patients may prefer to self-administer the drugs. Healthcare personnel should be aware of potential personal or cultural barriers to these medication routes.[13] Nursing, Allied Health, and Interprofessional Team InterventionsMinimizing pain or discomfort associated with medication administration can help improve patient experience and health outcomes. Utilizing local anesthetics when appropriate for the parenteral route or using lubricants in the rectovaginal medication route can be helpful. Nursing, Allied Health, and Interprofessional Team MonitoringBeing aware of and monitoring for potential immediate and delayed complications upon medication administration is essential. For example, in the central venous catheter, adverse effects such as bleeding, hematoma, thrombosis, or infection should be monitored closely.[28] Also, nursing staff should help maintain the area of the venous catheter sterile, check for its functionality regularly, and communicate with other healthcare team members when there are issues. 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