1. Drug Dosing and Delivery in Dentistry

Introduction

The choice of routes in which the medications are applied depends not only on convenience, a drug's properties and pharmacokinetics.

It is crucial to understand the characteristics of the various routes and associated techniques.

Many interprofessional healthcare team members are involved in administering medications to patients.

Each medication administration route has unique contraindications, and the healthcare team members need to recognize them.

This activity describes medication administration routes and explains the interprofessional team's role in improving care for patients who undergo medication administration.

Oral Route

Oral administration of medication is a convenient, cost-effective, and most commonly used medication administration route.

digestion begins in the mouth due to the enzymes

drug absorption PO

The primary site of drug absorption is usually the stomach and small intestine, and the bioavailability of the medication is influenced by the amount of drug absorbed across the intestinal epithelium.

begins in the mouth due to the enzymes

The first-pass effect PO

an important consideration for orally administered medications

It refers to the drug metabolism whereby the drug concentration is significantly diminished before it reaches the systemic circulation, often due to the metabolism in the liver (#1 organ of digestion)

Sublingual Route

A sublingual or buccal route is a form of the enteral route of medication administration that offers the benefit of bypassing the first-pass effect.

By applying the drug directly under the tongue (sublingual) or on the cheek (buccal), the medication undergoes a passive diffusion through the venous blood in the oral cavity, which bypasses the hepatic portal vein and flows into the superior vena cava.

Compared to sublingual tissue, which has highly permeable mucosa with rapid access to the underlying capillaries, buccal tissue is less permeable and has slower drug absorption.

can get higher concentration of drug and it is more rapid

drugs from plants

liable to cross membranes made of fat

ex: marijuana, opioids, aspirin

Rectal and Vaginal Routes

The Rectal and Vaginal routes are enteral routes of medication administration, and it allows for rapid and effective absorption of medications via the highly vascularized mucosa.

Similar to sublingual and buccal routes, rectally administered medications undergo passive diffusion and partially bypass the first-pass metabolism

Only about half of the drug absorbed in the rectum directly goes to the liver

the drug will still go to the blood system, but most is local

rectal mucosa is similar to oral mucosa

suppository = rectal

pessary = vaginal

Parenteral Routes

Intravenous injection is the most common parental route of medication administration and can bypass the liver's first-pass metabolism.

Superficial peripheral veins provide easy access to the circulatory system and are often utilized in the parenteral administration of medications.

The upper extremity is usually the preferred site for intravenous medication as it has a lower incidence of thrombophlebitis (blood vessel inflammation due to poking multiple times → clot) and thrombosis than the lower limbs.

blood taken in cubital region

The median basilic or cephalic veins of the arm or the metacarpal veins on the hand's dorsum are commonly used

In the lower extremity, the dorsal venous plexus of the foot can be used

Intramuscular Route

can be administered in different body muscles, including the deltoid, dorsogluteal, ventrogluteal, and vastus lateralis muscles.

Dorsogluteal site, or the buttock's upper outer quadrant, is a common site chosen traditionally for intramuscular injections by healthcare professionals, it poses a potential risk of injury to the superior gluteal artery and sciatic nerve.

On the other hand, the ventrogluteal site, or the anterior gluteal site, targets the gluteus medius muscle and avoids these potential complications; thus, it is recommended

he said dont know names

Subcutaneous Route

another form of the parental route of medication and are administered to the layer of skin referred to as cutis, just below the dermis and epidermis layers.

Subcutaneous tissue has few blood vessels; therefore, the medications injected undergo absorption at a slow, sustained rate.

Subcutaneous medication can be administered to various sites, including the upper arm's outer area and abdomen, avoiding a 2-inch circle around the navel, the front of the thigh, the upper back, or the upper buttock area behind the hip bone

Intraarterial Route

not commonly used for drug administration.

Injection of contrast material (radioopaque) after an arterial puncture is done for angiography.

The other uses of this route are for administering regional chemotherapeutic agents (will take it to the brain)

Treating malignant tumors of the brain.

What is the Intraarticular route?

joint

typically steroids when they suffer from pain

Transnasal drug

facilitates drug absorption by passive diffusion across the single-layered, well-vascularized respiratory epithelium directly into the systemic circulation.

An inhaled medication is delivered rapidly across the large surface area of the respiratory tract epithelium.

Drugs absorbed into the pulmonary circulation enter directly into the systemic circulation via the pulmonary vein, bypassing the first-pass metabolism.

The efficacy of drug delivery to the lungs depends not only on the drug particle size and morphology but also on the patient's respiratory physiology, such as tidal volume and tracheal inspiration velocity

ex: nasacort (hydrocortisone), narcan (naloxone), glucagon,

transdermal route

can deliver drugs through the skin.

uses common administration methods: local application formulations like transdermal ointments and gels, drug carriers like nanoparticles and liposomes, and transdermal patches

intraosseous route

useful, especially in neonates, for administering fluids and drugs when both peripheral and central venous accesses have failed

palatal injections

Clinical trials are now being conducted on its usefulness in administering medications in out-of-hospital cardiac arrest

It is also used for the administration of prophylactic antibiotics for regional surgeries

Drug Delivery to the CNS

The blood-brain barrier is a major obstruction to the delivery of drugs into the central nervous system.

Systemic administration of drugs for CNS action

Direct administration of drugs to the CNS - Intrathecal, into the cerebral arteries, into the brain parenchyma, and direct positive pressure infusion

Drug delivery using novel formulations like conjugates, and nanocarriers-based delivery systems (including polymeric nanocarriers, micelles, nanotubes, dendrimers, magnetic nanoparticles, and quantum dots

Drug delivery systems like pumps and catheters

Use of microorganisms like bacteriophages and bacterial vectors

Cell therapy - CNS implants of live cells or genetically engineered cells

Gene transfer - Direct injection into the CNS, intranasal instillation, retrograde axonal transport, or through vectors.

teratogenesis

defects in baby due to something mom consumed

warfarin vs aspirin

warfarin = anticoagulant

aspirin = antiplatelet

Contraindications

Each medication administration route has unique contraindications

Oral medication route is contraindicated for patients who cannot tolerate oral drugs, such as those who have altered mental status or have nausea or

A rectal route is contraindicated in patients with active rectal bleeding or diarrhea or after a recent rectal or bowel surgery. (all drugs can cause nause/vomiting/diarrhea)

severe psychosis = higher chance of non compliance

An intramuscular route is contraindicated in an active infection or inflammation at the site of drug administration, myopathies, muscular atrophy or coagulopathy (inflammation is acidic environment)

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 (2+ is intramuscular)

An intranasal medication is contraindicated in patients with nasal trauma, anatomic obstruction, the presence of a foreign body, or copious mucous or bleeding

An inhaled drug is contraindicated in patients with airflow obstruction (asthma/copd)

5 ‘Rights’ in Drug Dosing and Delivery

Right patient (name + DOB)

Right drug

Right dose

Right site

Right timing

It is essential to explain to patients how the medication will be administered, obtain consent for procedures when indicated, and help prepare patients before they receive their medication

The site of application of the drug 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.