Medication administration routes

Introduction: The route of administration is an important factor that influences the absorption of a drug. The interval between administration and the onset of action is determined by the route of administration. Biological delay is the interval between the administration of a drug and the development of the response.

Classification of the routes: The routes of administration of the drug can be classified as:

Oral or enteral route: it is the most used route for the administration of drugs.

Advantages of the oral route:

1. It is a safe, convenient and economical route.

2. Self-medication is possible.

3. Drug withdrawal possible.

Disadvantages of the oral route:

1. The onset of drug action is slow.

2. Medicines with a bitter taste cannot be administered.

3. Medications that cause nausea and vomiting cannot be administered.

4. The drug can be inactivated by gastric enzymes.

5. This route is not possible in an unconscious patient.

Enteric-coated pills and tablets: These are oral preparations coated with cellulose acetate or gluten. These coatings cannot be destroyed by the acidic juice of the stomach. Only alkaline intestinal juice removes these coatings. Thus, inactivation of the drug in the stomach is avoided. Thus, a desired concentration of the drug is released in the intestine.

Sustained-release or extended-release preparations (spansules): These are oral preparations that contain various coatings. Each coating dissolves at different time intervals releasing the active drug. Therefore, the drug is released more slowly over long periods of time.

Parenteral routes: routes of administration other than the oral (enteral) route are called parenteral.

Advantages of the parenteral route:

1. Absorption is fast and fast.

2. The exact dose of medicine can be given.

3. The drug enters the circulation in an active form.

4. It is useful in an emergency.

5. It is useful in case of an unconscious patient.

Disadvantages of the parenteral route:

1. Pain can be caused by injection.

2. Abscess procedures for injection are required.

3. Sterile procedures are required for injection.

4. It is an expensive route.

5. Self-medication is not possible.

in. Injection

1. Intradermal: the drug is injected into the layers of the skin, for example, the BCG vaccine.

2. Subcutaneous: By this route a non-irritating substance can be injected alone. The absorption rate is uniform and slow, so the effect is prolonged.

3. Intramuscular: the drug is injected deep into muscle tissue. The absorption rate is uniform and the onset of action is rapid.

4. Intravenous – A drug is injected directly into a vein.

Advantages:

(I) The drug enters the circulation in an active form.

(ii) The desired blood concentration can be obtained.

(iii) There is a quick and immediate effect.

(iv) It is useful in an emergency.

(v) It is useful in an unconscious patient.

Disadvantages:

(I) Drugs that precipitate blood components cannot be administered.

(ii) Adverse reactions, if they occur, are immediate.

(iii) No drug withdrawal possible.

5. Intra-arterial: In this route, a drug is injected into an artery. The effect of a drug can be localized to a particular organ or tissue by choosing the appropriate artery. Sometimes anticancer drugs are given this way.

6. Intraperitoneal – In this route, a drug is injected into the peritoneal cavity. In this way, fluids such as glucose and saline can be given to children.

7. Bone marrow: Injection into the bone marrow is very similar to intravenous injection. This route is useful when veins are not available due to circulatory collapse or thrombosis. In adults, the sternum is chosen and in children, the tibia or femur is chosen for injection.

B. Inhalation: Gases, volatile liquids, aerosols or vapors can be administered by this route.

Advantages:

1. Immediate drug absorption.

2. Localization of the effect in diseases of the respiratory tract.

Disadvantages:

1. Little capacity to regulate the dose.

2. Local irritation of the respiratory tract can increase its secretions.

3. Difficulty in the form of administration.

vs. Transacutaneous route: it is also classified as

I) Iontophoresis

ii) Floods

iii) Jet injection

iv) Adhesive units.

I) Iontophoresis: In this method, a drug penetrates deep into the skin using a galvanic current, for example salicylates. Anode iontophoresis is used for positively charged drugs and cathode iontophoresis is used for negatively charged compounds.

ii) Inunction: it is rubbing the drug on the skin. The drug is absorbed and produces a systemic effect, for example, nitroglycerin ointment for angina pectoris.

iii) Jet injection: this method does not require a spring. Then it is painless. Using a gun-like instrument with a micro-fine orifice, the drug solution is projected as a high-speed jet (dermojet). The drug solution passes through the superficial layers of the skin and is deposited in the subcutaneous tissue. This method is useful for mass inoculation.

iv) Adhesive units: It is a transdermal drug delivery system. It is available in the form of an adhesive unit. Deliver the drug slowly. So it produces a prolonged systemic effect. for example scopolamine for motion sickness.

D. Transmucosal route: it is further classified as

A) sublingual

B) Transnasal

C) transrectal.

A) Sublingual route: A tablet containing the drug is placed under the tongue and allowed to dissolve in the mouth, eg, nitroglycerin and isoprenaline.

Advantages of the sublingual route:

1. Quick start of action.

2. Termination of the effect by spitting out the tablet.

3. Inactivation of the drug in the stomach is avoided.

4. The drug enters the systemic circulation directly without inactivation in the liver.

B) Transnasal route: It is useful for drugs in the form of snuff or nasal spray. The drug is easily absorbed through the mucous membrane of the nose. for example, posterior pituitary dust.

C) Transrectal route: drugs can be absorbed through the rectum to produce systemic effects. eg aminophylline for bronchospasm, diazepam for us status epilepticus. The advantages of the rectal route are:

1. Gastric irritation is avoided.

2. It is useful in elderly and terminally ill patients.

me. New drug delivery systems:

I) Occusert: It is placed directly under the eyelid. It can release medications such as pilocarpine for long periods of time.

ii) Progestasert: It is an intrauterine contraceptive device. It produces a controlled release of progesterone within the uterus for a year.

iii) Prodrug: It is an inactive drug that, after administration, is metabolized into an active drug. For example, I-dopa is an inactive compound. After administration, it is metabolized to the active drug dopamine which is effective in Parkinson’s.

Local application: Medications in the form of powder, paste, lotion, drops and ointment can be applied locally to act at the site of application. Medications can be applied to the mucous membranes of the nose, conjunctiva, vagina, urethra, and rectum. The following are some preparations that are intended for local application:

1. Candle for urethra.

2. Vaginal pessary.

3. Suppository for vagina and rectum.

4. Enemas for the rectum.

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