The non-parenteral routes of drug administration refer to methods of delivering medications to the body that do not involve piercing the skin or bypassing the gastrointestinal tract. These routes include:
- Oral route
- Inhalation route
- Topical route / Inunction
- Instillation
- Insertion
- Insufflation
- Implantation.
1. Oral route
The oral route of drug administration refers to the intake of medications through the mouth, typically in the form of tablets, capsules, or liquids.
Advantages of oral route :-
- Safest route
- Self administration is possible
- It is the most common route preferred and used
- Wide availability of medications is available in oral form, making it a versatile and accessible route of administration.
- cheap and cost effective
- Painless
- Onset of action is 20 minutes.
- Safety and reversibility : In case of adverse effects or emergencies, the oral route allows for easy discontinuation of the medication or administration of specific antidotes.
- Patient-friendly : Swallowing pills or liquids is a familiar and comfortable method for most individuals, promoting patient acceptance and compliance.
Disadvantages of oral route :-
- Variable absorption : Oral medications can be subject to variable and unpredictable absorption in the gastrointestinal tract, leading to differences in drug levels in the bloodstream among individuals.
- First-pass metabolism : When drugs are absorbed through the gut, they first pass through the liver, where they may undergo metabolism before reaching the systemic circulation. This can reduce the bioavailability of certain medications.
- Gastrointestinal irritation : Some medications can irritate the gastrointestinal tract, leading to side effects such as nausea, vomiting, or stomach upset.
- Slow onset of action : Compared to other routes of administration, the oral route generally has a slower onset of action due to the need for digestion and absorption before the drug reaches the bloodstream.
- Patient compliance : Oral medications require patients to swallow pills or liquids, and adherence to prescribed dosing schedules can be challenging for some individuals, leading to inconsistent or missed doses.
- Interactions with food and other medications : Certain medications may interact with food or other medications in the gastrointestinal tract, affecting their absorption or effectiveness.
- Not suitable for patients with certain conditions : Patients with gastrointestinal disorders, difficulty swallowing, or impaired gastrointestinal motility may have limitations in absorbing oral medications effectively.
Subtypes of oral route
~> Sublingual route
The sublingual route is a method of drug administration where medications are placed under the tongue and absorbed through the mucous membranes into the bloodstream.
The rich blood supply and thin mucous membranes under the tongue contribute to efficient drug absorption.
Example – Nitroglycerin {used for the relief of angina (chest pain)}
Nitroglycerin
- Drug of Choice in Angina (chest pain)
- It is a photosensitive drug (thus it should be stored in a box where light can’t enter)
- Nursing responsibility while administrating Nitroglycerine- check BP at regular intervals and check expiry date frequently because expiry date of this medicine is of 6 months.
- Side effects of Nitroglycerine – Hypotension
sign and symptoms of Hypotension are 3 D’s
D – Dizziness
D – Drowsiness
D – Disoriented
These are common sign and symptoms of shock, acidosis, hypoxia and hypoglycaemia.
Advantages :-
- Rapid onset of action i.e., 3-5 minutes
- Avoidance of gastrointestinal degradation
- First-pass metabolism avoidance
- Ease of administration.
- Improved patient compliance as it is generally more convenient and easier for patients, especially those who have difficulty swallowing pills or have a sensitive gag reflex
- Reduced gastrointestinal side effects such as nausea, vomiting, or gastric irritation by bypassing the digestive system.
- Emergency administration is possible and this route is particularly useful in emergency situations where immediate drug action is required.
- Enhanced bioavailability: Bioavailability refers to the fraction of a drug that reaches the systemic circulation. Sublingual administration can offer high bioavailability for certain drugs because they are directly absorbed into the highly vascularized tissues under the tongue, allowing for efficient drug absorption.
Disadvantages :-
- Limited drug and dosage options availability.
- Taste and texture can be unpleasant for some individuals.
- Limited absorption capacity due to limited surface area for drug absorption.
- Risk of accidental swallowing before they are fully absorbed, resulting in reduced effectiveness or altered pharmacokinetics.
~> Buccal route
The buccal route refers to a method of administering drugs or medications by placing them between the cheek and gum, allowing the medication to be absorbed directly into the bloodstream through the buccal mucosa (the lining of the mouth).
This route of administration is considered an alternative to oral (swallowing) or intravenous (through the veins) administration.
Advantages and disadvantages of this route are same as of sublingual route.
2. Inhalation (pulmonary route)
The inhalation route refers to the administration of drugs or medications through inhalation, typically by breathing in the medication in the form of a gas, aerosol, or fine particles.
Inhalation is commonly used for respiratory conditions, such as asthma, chronic obstructive pulmonary disease (COPD), and respiratory infections
There are different methods of inhalation route that can be used and are as follows :
- Metered-Dose Inhalers (MDIs) : These handheld devices deliver a measured dose of medication in the form of a fine aerosol spray. The medication is released when the patient activates the inhaler while inhaling the mist.
- Dry Powder Inhalers (DPIs) : DPIs deliver medication in the form of a dry powder that the patient inhales. DPIs usually require a deep and forceful inhalation to effectively disperse the medication into the lungs.
- Nebulizers : Nebulizers are devices that convert liquid medications into a fine mist or aerosol, which can be inhaled through a mask or a mouthpiece. Nebulizers are often used for patients who have difficulty using MDIs or DPIs, such as young children or individuals with severe respiratory conditions.
Advantages of inhalation route :-
- The medication reaches the targeted area quickly.
- Provides rapid onset of action.
- It also allows for lower doses of medications compared to oral administration, as the drug directly acts on the respiratory system without going through the whole body.
- Inhalation is particularly effective for treating respiratory conditions because it delivers medications directly to the site of the problem.
Disadvantages of inhalation route :-
- Technique and coordination required for proper administration.
- Device limitations and challenges with certain inhalation devices.
- Risk of systemic side effects or adverse reactions.
- Potential for respiratory tract irritation or hypersensitivity reactions.
- Infection risk if inhalation devices are not properly cleaned and maintained.
- Limited availability of certain medications in inhalation form.
3. Topical route / Inunction
In this route the drugs are applied directly to the skin or mucous membranes. This route is used for local effects, such as treating skin conditions or delivering medications to specific areas.
“Inunction” refers to a historical method of drug administration that involves applying a medication topically by rubbing or massaging it onto the skin.
Example – ointments, sprays, cream, lotion, gel or powder.
Modern transdermal patches, creams, and gels have largely replaced the inunction method for topical drug delivery, as they provide more controlled and consistent dosing.
Advantages :-
- Systemic delivery : Medications can be absorbed through the skin and enter the bloodstream, allowing for systemic effects.
- Bypasses the digestive system : Drugs avoid degradation or inactivation that can occur in the gastrointestinal tract.
- Controlled absorption : The rate of drug absorption can be influenced, allowing for more controlled and gradual effects.
- Convenient : Inunction does not require swallowing pills or using needles, making it a convenient option for certain patients.
Disadvantages :-
- Variable absorption : The extent of drug absorption can vary between individuals and may be influenced by factors such as skin condition and thickness, making it less predictable compared to other routes.
- Skin irritation : Certain medications or ingredients in the ointment or oil-based preparation used for inunction can cause skin irritation or allergic reactions.
- Limited application : The inunction route is primarily suitable for medications that can be absorbed through the skin. Some drugs may not be effectively absorbed using this method.
- Lack of precise dosing control : It can be challenging to achieve precise and consistent dosing with inunction, as factors like the amount of medication applied and the duration of massage can affect drug absorption.
4. Instillation
The instillation route refers to the administration of liquid medications directly into certain body cavities or openings. Examples are eye, ear or nasal drops.
Subtypes :
a) Ophthalmic (eye) Instillation :
Medications in the form of eye drops, ointments, or gels are instilled into the eyes. This route is commonly used for treating eye conditions such as infections, glaucoma, dryness, or inflammation.
Key points to remember while instillation of eye drops and eye ointments :
- Site of eye drops instillation – lower middle conjunctival sac
- Eye ointment application – apply from outer canthus (the corner or angle where the upper and lower eyelids meet) to the inner canthus of eye whereas, eye irrigation is performed from inner canthus to the outer canthus.
- After applying the ointment press the inner canthus of eye with a clean finger to stop systemic absorption via lacrimal duct (tear duct).
- Instill eye drop first then followed by the eye ointment if both are necessarily to be administered at the same time.
- Keep the distance of the dropper from the eye at least 2cm / 1 inch.
- Waiting for at least 5–10 minutes between eye drops, if more than one drop is required.
b) Otic (ear) Instillation :
Medications in the form of ear drops or sprays are instilled into the ear canal. Otic instillation is used for treating ear infections, wax buildup, or other ear-related conditions.
• Method : The patient typically lies on their side with the affected ear facing upward.
• Technique : Proper technique is essential to ensure effective administration and minimize the risk of complications.
It is important to :
- Hold the medication bottle at room temperature
- Tilt the head to the side
- Gently pull the earlobe upward and backward to straighten the ear canal in adult patients (age > 3yrs) and pull earlobe downward and backward in infants (age < 3yrs.)
- Precautions : It is essential to avoid inserting any objects into the ear canal, such as cotton swabs, as they can push the wax further in or damage the delicate structures of the ear.
c) Nasal Instillation :
Medications are instilled into the nostrils as nasal drops or sprays. This route is employed for treating nasal congestion, allergies, sinusitis, or other nasal conditions.
• Method : Nasal instillation involves the administration of liquid medications in the form of drops or sprays into the nostrils. The patient typically tilts their head back slightly, inserts the dropper or sprayer into the nostril, and administers the prescribed number of drops or sprays into each nostril.
• Proper Technique : This typically involves inserting the dropper or sprayer into the nostril and directing the spray or drops toward the back and sides of the nasal passage. It is important to use a gentle, controlled spray and to avoid spraying too forcefully or directly toward the nasal septum.
• Precautions: It is advisable to blow the nose gently before administering nasal instillation to ensure clearer nasal passages. It is important to avoid sharing nasal medications to prevent the spread of infections. If there are any signs of an allergic reaction, worsening of symptoms, or persistent nasal issues, it is recommended to seek medical advice.
d) Urethral Instillation :
Medications are instilled into the urethra, typically in the form of a gel or solution. Urethral instillation is used for certain urological conditions, such as urinary tract infections or interstitial cystitis.
• Method: Urethral instillation involves the insertion of a medication, typically in the form of a gel or solution, into the urethra. This is done using a sterile applicator or syringe designed for urethral administration.
• Proper Technique : It involves gently inserting the applicator or syringe into the urethra, typically a short distance, and administering the medication according to the healthcare professional’s instructions. It is important to use sterile equipment and maintain proper hygiene during the procedure.
• Precautions: It is important to communicate any concerns or discomfort experienced during urethral instillation with the healthcare professional. Adhering to recommended guidelines and precautions can help minimize the risk of complications.
5. Insertion
Insertion means introducing solid forms of drugs into the body orifices. e.g., suppositories – introduced into the rectum and vagina.
Rectal Insertion :
Medications are instilled into the rectum in the form of suppositories or enemas. This route is employed for localized treatment of conditions like hemorrhoids, rectal inflammation, or constipation.
• Method: Rectal instillation involves inserting a suppository or administering an enema into the rectum. Suppositories are solid or semi-solid medications that melt or dissolve upon insertion, releasing the medication. Enemas are liquid solutions that are introduced into the rectum via a tube or applicator.
• Proper Technique: Proper technique is crucial for effective and safe rectal insertion and instillation. For suppositories, it involves gently inserting the suppository into the rectum using a clean finger or a specialized applicator. Enemas require following specific instructions regarding the volume of the solution, insertion of the applicator, and positioning during administration.
• Precautions: It is important to maintain proper hygiene, follow storage instructions for suppositories, and use appropriate lubrication if needed for insertion. If discomfort or resistance is experienced during insertion, it is advisable to consult a healthcare professional.
6. Insufflation
It is the administration of drug in the form of powder, vapour or air into a wound or body cavity by blowing with an insufflator.
7. Implantation
The implantation route of drug administration involves the placement of a solid or semi-solid device, known as an implant, into the body. The implant slowly releases the medication over time, providing a sustained and controlled drug delivery.
