Drug Application Routes

• Routes for drug application are determined by the drug's target and the condition of the application site.
• When administering drugs, the amounts and application sites should allow the active substance to reach the place of effect in MEK (minimum effective concentration).

Local Application Ways

• Drug affect should be on the body surface
• Route of drug application that includes:
  • Epidermal
  • Intracutaneous
  • Intrathecal
  • Intrapleural
  • Intraperitoneal
  • Intracardiac
  • Intraarticular
  • Intrauterine
  • Intravaginal
  • Into the rectum and colon
  • On the conjunctiva
  • Intranasal and Buccal

Epidermal Application

• Used for localized lesions in accessible areas
• Used for drugs with minimal or no absorption
• Has no or minimal systemic side effects or toxicity

Intracutaneous Application

• Applied to the dermis layer, located just below the epidermis.
• Sterile solutions and test serums for allergy and bacteriology tests are applied

Conjunctiva Application

• Used in various infections
• Ophthalmic preparations must be sterile

Intranasal Application

• Used for diseases of the nasal mucosa and paranasal sinuses
• Applied for anti-inflammatory, vasoconstrictor, local anesthetic drug solutions
• Systemic application is also possible

Buccal (Intraoral) Application

• Used for mouth and gum infections

External Ear Canal Application

• Medication is applied for diseases of the external ear canal or eardrum

Intrathecal Application

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

Intracardiac Application

• In emergency situations or for cardiac resuscitation during cardiac surgery
• Stimulant drugs such as adrenaline administered directly to the heart

Intraperitoneal Application

• In some cases of inflammation of the peritoneum, injections may be made into the abdominal cavity

Intraarticular Application

• In some joint diseases, corticosteroids or antibacterial drugs can be injected into the joint

Rectal and Colonic Application

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

Intrauterine Application

• Oxytocic hormone is injected into the myometrium to accelerate uterine contraction after cesarean sections

Intravaginal Application

• Medications are administered into the vagina in the form of a pessary
• Drugs in the form of foam and gel are also used to prevent pregnancy

Systemic Drug Application Methods

• Includes:
  • Enteral
  • Parenteral
  • Transdermal
  • Inhalation

Enteral Application

• Oral, sublingual, or rectal administration

Parenteral Application

• Intravenous, subcutaneous, intramuscular, or into the bone marrow
• Drugs are not absorbed from the gastrointestinal tract or broken down there
• Injected into a vein or tissue with a sterile syringe and starts to work quickly

Transdermal Application

• Application of the drug to the skin in a special pharmaceutical form
• The drug is absorbed from the skin and enters the circulation

Inhalation Application

• Lipophilic drugs in gas or vapor form pass through the alveolar membrane and enter the general blood circulation by inhalation

Oral Application

• The most commonly used, most practical, and most economical route
• Drugs must pass through the liver after absorption before entering the systemic circulation
• Some drugs may be inactivated and their absorption may not be complete

Sublingual Application

• Used in cases where the drug effect is desired to start very quickly
• Ability to quickly dissolve and create an effect with small amounts
• Highly soluble in fat
• Drugs in the form of small tablets

Rectal Administration

• A local or systemic effect is achieved by absorption from the rectal mucosa
• Administered in the form of suppositories or enemas
• Is more commonly used in patients who cannot take oral medication and in infants

Parenteral Administration Requirements

• Drugs that cannot be absorbed or broken down in sufficient amounts from the gastrointestinal tract if given orally
• Drugs that require rapid onset of effect, such as in emergency situations
• The patient is unconscious, unable to swallow, or experiencing nausea, vomiting, or diarrhea, etc

Disadvantages of Parenteral Administration

• Painful
• Can cause vascular or tissue damage
• Creates psychological stress
• Cannot be administered by the patient alone
• Has disadvantages such as the expensive pharmaceutical form used

Intravenous (IV) Administration

• Drugs that are water-soluble or water-mixable
• Use when rapid effect is desired
• If the patient is unconscious and cannot swallow the drug, this application is preferred
• Bioavailability is usually 100%
• Drug solutions up to 10 ml are injected in 1-2 minutes
• Intravenous infusion is the slow administration of large volumes of drug solutions

Disadvantages of Intravenous Administration

• Only water-soluble drugs can be administered
• Oily solutions and suspensions are not administered intravenously (embolism)
• Drugs with low water solubility may precipitate in the vein if injected rapidly
• Administered drug cannot be retrieved
• High risk of anaphylaxis
• Irritant drugs may cause tissue damage if extravasation occurs

Intramuscular (IM) Administration

• Injecting the drug into the appropriate muscle tissue
• Gluteal or deltoid muscle is usually preferred
• The volume of solution administered should not exceed 5 ml
• Absorption of the injected drug is mostly affected by blood flow in that area
• Massage or exercise increases absorption

Subcutaneous Administration

• The outer surface of the humerus or femur region is often preferred
• Maximum of 2 ml of solution should be applied to prevent pain on the skin
• Irritant drugs should be applied intramuscularly rather than subcutaneously
• Some drugs are placed under the skin in the form of implants or pellets

Intraosseous Injection

• In infants and sometimes adults
• If veins cannot be found, the drug is injected into a suitable bone marrow (sternum) and from there it passes rapidly into the blood
• Very rare method

Transdermal Administration

• Application of the drug to the skin surface for systemic effect
• Highly lipophilic and small dose effective drugs such as nitroglycerin, scopolamine, clonidine, fentanyl, testosterone are applied using a transdermal therapeutic system (patch)

Inhalation Administration

• Alveoli have a very large surface area and a highly permeable membrane, and the blood flow rate in the lungs is also very high
• Pass through the alveolar membrane in the lungs and enter the bloodstream
• Drugs that are gaseous and vaporous (sevoflurane) and have high fat solubility, such as general anesthetics (nitrous oxide), and asthma and COPD drugs are administered

Application Areas of Drugs and Pharmaceutical Forms (Local)

• Epidermal: Ointment, pomade, cream, lotion, powder, soap, solution, liniment, plaster, paste
• Intranasal: Nasal drops and Nasal spray
• Intravaginal: Vaginal suppository, Vaginal tablet, ointment, gel, foam
• Buccal: Lozenge, solution, gargle
• Rectal: Ointment, suppository, enema
• Colon: Enema
• External ear canal: Otic (ear) drops (solution, suspension)

Application Sites of Drugs and Pharmaceutical Forms (Systemic)

• Oral: Solid and Liquid forms
• Solid drug forms: Tablet, dragee, capsule, film-coated tablet, enteric tablet, chewable tablet, packet, effervescent tablet, cachet, pill
• Liquid drug forms: Syrup, elixir, solution, suspension, drop (concentrated solution), lotion, emulsion, extract
• Parenteral: Solution or suspension for injection, emulsion (ampoule, vial, powder for reconstitution), implantation pellet
• Inhalation: Gas, vapor, aerosol, inhaler, nebulizer
• Transdermal: Patch (TTS), ointment
• Other: Nasal spray