Introduction:
Thеrе arе diffеrеnt ways to givе mеdicinе to hеlp our bodiеs. Each way has good things and somе problеms too. Wе will lеarn about thеsе ways in dеtail. From taking mеdicinе by mouth to brеathing it in, or putting it on thе skin, wе’ll еxplorе how thеsе ways work and whеn thеy’rе usеful.
Lеt’s start this journеy to undеrstand how wе givе mеdicinе to our bodiеs through diffеrеnt ways and what еach way is good for.
Drugs can be administered by any of the following routes:
1. Intestinal (Enteral) route
2. Inhalation
3. Local (Topical) application
4. Parenteral routine
1. Intestinal Routes (GIT)
a) Oral route: The oral route of administration is the most common route and doses which are not otherwise specified are considered to be oral doses Drugs given orally are absorbed from different parts of the gastrointestinal tract.
Advantages: The oral route (i) is natural, convenient and most acceptable, (ii) is the safest, (iii) is the most economical, (iv) allows self medication, (v) allows withdrawal of the drug in cases of toxicity. Medicaments need not be sterile and so are cheaper. Therefore, the maximum number of drugs is administered orally.
Disadvantages: (i) Onset of action is slow, so not useful in an emergency. (ii) Absorption is irregular and unpredictable due to presence or absence of food in the gastrointestinal tract (GIT). (iii) Not suitable during vomiting and severe diarrhoea. (iv) Cannot be used for an unconscious patient. (v) Some drugs like insulin and oxytocin are destroyed by the GIT fluids and drugs like streptomycin are not absorbed from the GIT. (vi) Drugs absorbed
from the small intestine enter the liver via portal circulation. Sorne drugs like B-Blockers, such as propranolol, pethidine are extensively metabolised by the liver and this may reduce the bio-availability of the drug. This phenomena is called hepatic 1st pass effect. (vii) Some drugs may be metabolised in the intestine and the process is called intestinal 1 st pas effect. (viii) Irritant drugs may cause nausea and vomiting. (ix) Some drugs with a bitter and unpalatable taste are not acceptable by this route.
Some of the dosage forms which can be administered orally are tablets, capsules, powders, granules, mixtures, suspensions, syrups and emulsions. Solid drugs are administered by placing the drug in the mouth and swallowed with the help of a suitable liquid mainly water.
b) Sublingual: In this case tablet is placed under the tongue and allowed to dissolve from where it gets absorbed rapidly through the mucous membrane.
Advantages: (i) Absorption is rapid and uniform, so it is useful in an emergency like angina. Drugs generally given by this route are nitroglycerin, isoprenaline, and methyltestosterone, (ii) the liver is bypassed so drugs metabolised in the liver during first pass can enter directly into systemic circulation, (iii) the remaining drug can be spat out after the desired effect has been obtained or some toxic effects appear.
Disadvantages: Drugs with a bad taste, bad smell or of an irritant nature are unsuitable for this route; (ii) not convenient if the dose of drug is large or required over long period
c) Rectal route: Drugs in the form of suppositories, ointment or enema can be given.
Advantages: This route for systemic action is employed in conditions when (i) oral medication would not be retained or absorbed properly such as during severe nausea and vomiting or in paralytic ileum, (ii) the drug is liable to be destroyed by the GIT fluids or (iii) the drug should by pass the liver. (iv) Evacuant enema is done to remove the faecal matter before surgery, delivery and X-rays of the GIT. The volume of enema may be about 600
ml. (v) The retention enema is employed for local conditions like ulcerative colitis or systemic absorption. The volume of fluid for this is 100-120 ml. Disadvantages: (i) It is embarrassing to the patient, (ii) absorption from this route is slow, irregular and unpredictable.
2. Inhalation
In this route, the drug may be administered in the form of gas, vapours or as aerosols. Moreover, medicinal gases such as oxygen and volatile or gaseous anaesthetics have to be administered by this route. Solid drugs in the form of aerosols are administered by this route for local or systemic effects.
Advantages: (i) Rapid onset of action. Drugs are absorbed by the pulmonary endothelium very rapidly. In respiratory diseases like asthma, bronchodilators like salbutamol can be given in the form of aerosols. (ii) When sterility is important a dose can be removed without contaminating the remaining material. (iii) When administration is discontinued the volatile drug diffuses back and is rapidly eliminated in expired air. Thus controlled administration is possible. (iv) Small doses. (v) Minimal systemic side effects.
Disadvantages: (i) Irritant vapours cause inflammation of the respiratory tract and increase secretion, (ii) Expensive apparatus is required for administration of aerosols or gases.
3. Local Application
Local application is the simplest mode of administration of drugs at the site where the effect is desired. This method is used for topical effects on the skin or mucous membrane or deeper tissues. Generally the action of the drug is limited to the area of application. Thus the optimum concentration can be attained with the minimum quantity of the drug and in general, without any systemic effects. The sites where drugs are applied locally are the skin, eyes, ears, nose, throat, teeth, gum, rectum, vagina, urethra. Common dosage forms of drugs used are dusting powders, ointments, creams, emulsions, gels, lotions, paints, sprays, gargles, liniments, plasters and drops. The choice of dosage form depends on the site of application. Special types of jellies and vaginal tablets are available for local application to the vagina. Lozenges and paints are also used for local effects on the throat. Many drugs used in dentistry are also given by local application.
Transdermal Drug Delivery Systems (TDDS)
The systemic absorption of drugs from the cutaneous route is generally unintended and negligible. However, in recent years emergence of “transdermal patches” for slow and sustained absorption of drugs into systemic circulation across cutaneous tissues is a novel approach. The drugs may be absorbed through hair follicles, sweat glands or sebaceous glands. The dosage forms for such use are designed accordingly. Advantages of this method are that the drug is absorbed slowly and maintains a constant level in the blood, it avoids first by pass metabolism in the GIT and liver and improves patient compliance. Drugs with a short biological half life can be administered once a day e.g. nitroglycrin transdermal patches. Transdermal patches of hysocine, clonidine, estradiol and nicotine are also available. Such preparations of other drugs are under evaluation.
4. Parenternal Preparation
This refers to the administration of drugs which take them directly into tissue fluid or blood without having to cross the intestinal mucosa. With all forms of parenteral administration, sterile conditions are essentially to be maintained.
Advantages: (i) Sure and immediate onset of action, so useful in an emergency, (ii) no destruction of drug by GIT fluids and the liver, since the liver is by passed, (iii) can be used for unconscious and non- cooperative patients, (iv) can be used in the presence of vomiting and diarrhoea, (v) drugs not absorbed from GIT can be given.
Disadvantages: (i) Needs sterile procedures for injections, (ii) painful. (iii) chance of local tissue injury, (iv) self medication is difficult or not possible (v) less safe, (iv) expensive as compared to oral route.
Conclusion:
Giving mеdicinе has many ways, and еach way has its good things and somе not-so-good things. Whеn wе givе mеdicinе by mouth, it’s еasy and most pеoplе likе it. But somеtimеs, it’s slow to start working. Brеathing mеdicinе in is quick, еspеcially for brеathing problеms, but it nееds spеcial еquipmеnt.
Putting mеdicinе on thе skin or using it locally in cеrtain body parts is good for fixing just that spot. And giving mеdicinе dirеctly into thе body without going through thе stomach can bе fast but nееds carе and clеanlinеss.
Knowing thеsе ways hеlps doctors choosе thе bеst way to givе mеdicinе for diffеrеnt pеoplе and situations. As mеdicinеs gеt bеttеr, undеrstanding thеsе ways bеcomеs morе important to givе thе right trеatmеnt in thе bеst way possiblе.