Medication Administration

• As a medication is administered, the body starts removing it, the medication's dose, administration route, and the patient's clinical status determine its duration and effectiveness.

Principles of Pharmacokinetics

• Medication profile indicates onset, peak, and duration relate to absorption and distribution.

Routes of Medication Administration

• The administration route is determined by physical and chemical properties of the drug, routes available, and how quickly the effects are needed.
• Bioavailability is the percentage of unchanged medication that reaches systemic circulation and varies by medication.

Oral, Orogastric, and Nasogastric Tube

• The patient must be responsive, able to swallow, or have a nasogastric or orogastric tube.

Endotracheal

• This route is unreliable, requiring 2 to 2.5 times the IV dose, followed by a 5 to 10 mL flush of sterile water or normal saline.

Intranasal

• Liquid medications are converted into a mist that is sprayed into one or both nostrils.
• This route offers rapid absorption, nearly 100% bioavailability, and eliminates needlestick injury risk.

Intravenous

• IV administration is the preferred method in the prehospital setting.
• A catheter is inserted into a peripheral or external jugular vein
• This allows 100% bioavailability and a quick onset.
• Access may be difficult in some patients, cause pain or infection, can be time consuming, and certain drugs can cause pain and tissue damage.

Intraosseous

• This route involves needle insertion into bone and lasts up to 24 hours
• It is contraindicated in fractured bones.

Intramuscular

• Medication is injected into a large muscle, with 75% to 100% bioavailability.
• Confirm the medication, injection muscle, and injection technique are suitable.

Subcutaneous

• Medication is injected into subcutaneous tissue.
• Only indicated for certain medications and slower absorption may prevent adverse cardiovascular effects.

Dermal and Transdermal

• Medication is administered through patches releasing a constant dose over a long period.
• Patches may contain a large quantity of medication, which can affect a patient's clinical presentation or interfere with other medications administered.

Sublingual

• Medication is placed under the tongue, resulting in low bioavailability and requiring large doses.
• Patients must be conscious and alert; often used for nitroglycerin.

Inhaled or Nebulized

• This route is limited to oxygen and antidotes.
• Liquid nebulization carries a risk of bronchospasm.

Rectal

• Preferred over oral when patients are unresponsive, having seizures, vomiting, or unable to swallow; bioavailability may exceed 90%.
• Medications are manufactured as suppositories, but absorption is unpredictable.

Ophthalmic

• Generally limited to ocular anesthetic agents

Other Methods

• Hemodialysis, where blood is pumped through a dialysis machine.
• Paramedics should only use routes for which they are trained.

Distribution of Medication

• Medication movement through the body is influenced by chemical and physical properties, and patient factors.
• Medications must move through barriers that prevent foreign substances from entering the body.

Osmosis

• Osmosis is used to enhance the distribution of certain medications.
• Allows IV fluids to leave the intravascular space and enter various tissues and cells

Filtration

• Filtration redistributes water and particles
• Hydrostatic pressure forces fluids through semipermeable membranes.

Epithelial Cells

• Epithelial cells create a continuous barrier.
• Small, nonionic, and lipophilic molecules pass easily through cell membranes.
• Large hydrophilic and ionic molecules must find another route of entry (pinocytosis, facilitated diffusion, active transport).

Medication Movement Barriers

• Medications must also move through capillary walls to reach some tissues.
• Consisting of the blood-brain, blood-placenta, and blood-testes barriers.
• Blood passes freely through capillaries in the kidney, thyroid, pancreas, lungs, and peritoneum.

Plasma Protein Binding

• Medication molecules temporarily attach to proteins in the blood plasma.
• Medication concentration may change as plasma protein levels change or another medication that binds with plasma protein is introduced.

Lipophilic Medications

• Lipophilic medications sequester in the fat tissues of obese persons.
• The medication is released slowly, causing prolonged effects.

Volume of Distribution

• Defines the extent a medication will spread within the body.
• Medications with a lower volume of distribution have higher plasma levels.

Medication Metabolism

• Biotransformation: Medication becomes a metabolite
• Active metabolites are capable of pharmacologic activity, while inactive metabolites lack the ability to alter cell processes or body functions.

Effects of Biotransformation

• Inactive substances can become active.
• Active medication can change into another active medication.
• Active medication can be inactivated, or transformed into a substance easier to eliminate.

Liver

• Biotransformation mostly occurs in the liver
• The P-450 system chemically alters medication structures.
• The kidneys, skin, lungs, GI tract, and other tissues may also cause biotransformation.
• Biotransformation makes medications easier to eliminate.

Medication Elimination

• Primarily occurs via the kidneys and is influenced by a variety of factors.
• Zero-order elimination: a fixed amount is removed during a certain period.
• First-order elimination: the rate is influenced by the substance’s plasma levels.

Half-Life

• The time needed for metabolism or elimination of 50% of a substance in plasma.
• It can be altered by disease states, changes in perfusion, and medication interactions

Rate of Elimination

• Medications are administered at a dose and frequency equal to the body’s rate of elimination.
• Smaller amounts of medication can be eliminated in expired air.

Reducing Errors

• Medication decisions are often based on memory and happen in stressful situations.
• Paramedics could make a cognitive or technical error.

Rights

• Right patient
• Right medication
• Right dose
• Right route
• Right time
• Right documentation and reporting
• Right assessment
• Right to refuse
• Right evaluation
• Right patient education

Other Error Reducers

• Perform a verbal read-back of orders.
• Call out medication name and dose.
• Label syringes.
• Bring along the patient’s home medications.
• Use a reliable reference source.
• Have a partner confirm the dose.