Drug Administration Routes

• Drugs need to be present at a certain concentration (MEK, or minimum effective concentration) in order to have an effect.
• When drugs are administered, the amount and where they are applied to, must ensure the active substance reaches the necessary place to have the necessary effect at MEK.
• Routes of administering drugs separate into 2 categories based on what part of the body the drug is targeting and the condition of that location.
• The choice of administration route relys on the drug and patient considerations.

Local Application Ways

• The place where a drug is meant to have an effect is on the body's surface
• Include epidermal, Intracutaneous, intrathecal, Intrapleural, Intraperitoneal, intracardiac, Intraarticular, intrauterine and Intravaginal
• Also include administering into the rectum and colon, onto the conjunctiva, and intranasal and buccal administrations.

Epidermal

• Used only for localized lesions in accessible areas, for drugs that have no to minimal absorption from these areas.
• Presents no or minimal systemic side effects and/or toxicity.

Intracutaneous

• Involves application to the dermis layer, which lies under the epidermis.
• Sterile solutions and serums are applied for allergy/bacteriology tests.

On the Conjunctiva

• Used for various infections.
• Ophthalmic preparations described as 'colir'
• Ophthalmic preparations need to be sterile.

Intranasal Application

• Used in diseases within nasal mucosa and paranasal sinuses with anti-inflammatory, vasoconstrictor, and local anesthetic drug solutions.
• Systemic application can be possible.

Buccal

• Used for mouth and gum infection treatments.

External Ear Canal

• Used to treat various different external ear canal and/or eardrum diseases.

Intrathecal

• Sterile antibiotic or local anesthetic solutions administered to create a local effect on the meninges or spinal nerve roots.

Intracardiac

• Used in emergency situations or for cardiac resuscitation during cardiac surgery, stimulant drugs like adrenaline can be administered directly to the heart.

Intraperitoneal

• Used when inflammation of the peritoneum is present, with injections being directed into the abdominal cavity.

Intraarticular

• Used to treat joint diseases, corticosteroids or antibacterial drugs are injected into the joint.

Rectal and Colonic Application

• Suppository, enema, or ointment-shaped preparations are used for superficial lotions of the rectum, hemorrhoids, and some diseases of the colon.

Intrauterine

• Oxytocic hormone injected into myometrium to speed up uterine contraction following cesarean sections, helps reduce bleeding.

Intravaginal

• Medications administered into the vagina, using a pessary.
• Spermicide drugs in foam or gel used to prevent pregnancy.

Systemic Drug Application Methods

• Enteral drug application includes oral, sublingual, and rectal administrations.
• Parenteral involves intravenous, subcutaneous, intramuscular, and bone marrow administrations
• A drug isn't absorbed from the gastrointestinal tract or broken down, also includes sterile syringes, and starts working quickly

Transdermal

• Involves applying a drug to the skin in a special pharmaceutical form, which ensures absorption from the skin into the circulation

Inhalation

• Involves lipophilic drugs in gas or vapor passing through the alveolar membrane and enter the general blood circulation through inhalation.

Oral Administration

• Most commonly used, practical and economical
• Orally administered drugs pass through the liver for absorbtion before entering systemic circulation
• Some drugs get inactivated through this process, and their over all absorption can be incomplete

Sublingual

• For where a drug effect is needed instantly
• Involves quickly dissolving the product
• Includes small amounts of a drug
• Is very soluble in fat
• Is usually present in drugs in smaller tablets

Rectal Administration

• Both local and systemic effects achieved through the rectal mucosa's absorption of drugs
• Drugs can be administered through suppositories or as enemas
• Is most suitable for patients who cannot take oral drugs, and infants.

Parenteral Administration

• Drugs that generally cannot be absorbed or sufficiently broken down by the gastrointestinal tract when taken orally.
• Drugs requiring rapid onset
• Can be used on experiencing patients who are unconscious, unable to swallow, or experiencing nausea, vomiting or diarrhea

Disadvantages of Parenteral Administration

• Can be painful
• Can lead to vascular and tissue damage
• Causes physiological distress
• Requires administration by external parties
• Can be expensive

Intravenous

• Only water-soluble and water-mixable drugs can be administered
• Preferred where a rapid effect is needed
• Bioavailability is usually 100%
• Involves injecting drug solutions up to 10ml in 1-2 minutes.
• Intravenous infusion is the slow administration of large volumes of drug solutions (over 1-2 hours) into a vein.

Disadvantages of Intravenous Injections

• Intravenous injections only administer water-soluble drugs
• Oily solutions and suspensions cannot be administered this way
• Drugs with a low water-solubility can cause a precipitate in the vein if injected rapidly
• Once administered, a drug can't be retrieved
• Causes a high anaphylaxis risk
• Irritant drugs can cause tissue damage should extravasation occur.

Intramuscular

• Involves injecting the drug to the relevant muscle tissue(s)
• Gluteal and deltoid muscles usually preferred
• Max solution volume is 5ml
• How well the drug is injected and absorped depends on blood flow to the area
• Absorption is increased by massage or exercise

Subcutaneous

• Injections made under the skin
• Outer surface of the humerus or femur region is often preferred.
• Maximum of 2 ml of solution should be administered to prevent pain
• Irritant drugs should be applied intramuscularly rather than subcutaneously.
• Drugs placed under the skin in the form of implants or pellets (compressed tablets), are release slowly and regularly.

Intraosseous Injection

• For infants and adults whose veins cannot be located for injection
• A drug is injected straight into bone marrow(sternum) and passes into the blood relatively fast
• A very rare approach/method

Transdermal Patches

• The drug is applied to areas of skin to have a systemic effect
• Is highly lipophilic
• Small and effective drugs are used (like nitroglycerin, scopolamine, clonidine, fentanyl and testosterone) and are applied in this way
• Involves therapeutic systems with transdermal patches

Inhalation Applications

• It is advantageous in that alveoli have a high level of permeability and large surface area, blood flow in the lungs is consistently high
• When inhaled, they quickly pass through the alveolar membrane into the bloodstream
• Drugs that are gaseous and vaporous (sevoflurane) and have high fat solubility, such as general anesthetics (nitrous oxide) are used
• Treatments for asthma and COPD are administered through this process

Local Application Forms

• Epidermal involves ointment, pomade, cream, lotion, powder, soap, solution, liniment, plaster and paste
• Intranasal uses nasal drops and sprays
• Intravaginal medications are; vaginal suppositories, vaginal tablets, ointments, gels and foams
• Buccal application forms includes lozenges, gargles and solutions
• Rectal makes use of ointments, suppositories and enemas
• Colon makes use of enemas
• The external ear canal makes use of mainly otic drops, containing solutions and or suspensions

Systemic Application Forms

• Oral medications can come in tablets, dragees, capsules, film-coated tablets, enteric tablets, chewable tablets or packets
• Oral medications can also come in liquid forms such as; syrups, elixirs, solutions, suspensions, drops (concentrated solutions), lotions and extracts.
• Parenteral drugs come in solution or suspension for injection, either as ampoules, vials, or powder for reconstitution
• Can also come as implantation pellets
• Inhalation medications include gas, vapor, aerosol, inhalers, and nebulizers
• Transdermal administrations make use of patches and ointments
• Others such as nasal sprays