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Lecture 4. Therapeutic alternatives: These are drug products that contain different active ingredients but of the same pharmacologic class and used for the same therapeutic objective.
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Therapeutic alternatives: • These are drug products that contain different active ingredients but of the same pharmacologic class and used for the same therapeutic objective. e.g.1Diclofenac-containing drug products could be used instead of those containing Indomethacin or Ibuprufen (as NSAI). e.g.2 Naphazoline hydrochloride and Phenylephrinehydrocholride (as vasoconstrictors).
Routes of administration • The majority of drugs must be absorbed into bloodstream in order to reach the site of action. • They affect the rate and efficiency of absorption. • A particular drug may be available in different forms. • Many drugs are available as tablets and injection.
The choice between tablets and injection depends on a number of factors including: • The severity of illness. • The urgency with which the drug effect is needed • The part of the body requiring treatment. • The patient’ s general state of health (ability to swallow).
Oral administration • Is the most frequently used method of administration. • Most drugs are absorbed into bloodstream through the walls of the intestine. Advantages: Safe, easy and economic.
Disadvantages: Unsuitable in certain medical conditions and for some drugs such as: • Emergency due to slow onset of action • Presence of nausea, vomiting and diarrhea. • Drugs destroyed by gastric acid e.g. Penicillin. • Drugs destroyed by GIT enzymes e.g. Insulin. • Drugs inactivated by first pass metabolism in the intestinal mucosa e.g. Nitroglycerin. • Drugs that interact with food e.g. Tetracycline.
Swallowing difficulty: • Unconscious patients • Children refuse to swallow oral medications • Geriatrics often have difficulty in swallowing
Sublingual administration The drug is inserted under the tongue in the form of tablet. Advantages: • Rapid onset of action (less than 5 minutes). • Suitable for drugs subjected to first pass mechanism e.g. Nitroglycerine.
Disadvantages: • Short duration of action (the length of time that a drug gives a therapeutic effect). • Unsuitable for irritant drugs and drugs with bitter taste.
Parenteral administration Drugs may be injected into body to produce systemic effect. Advantages: • Rapid response. • Lower dose and side effects. • Person’s intolerance to a drug when taken by mouth (irritant drug). • Suitable for drugs destroyed by gastric acid. • Suitable for drugs with poor GIT absorption.
Disadvantages: • Dangerous as it is difficult to remove the drug once it is administrated. • Invasive and painful (lower compliance). • Sterile techniques are necessary to avoid the risk of infection. • Need special experience.
Types of injections: • Intravenous (IV) • Intramuscular (IM) • Subcutaneous (SC) • Intradermal (ID) The type of injection used depend on: • The nature of drug • The condition being treated.
Intravenous route Administration and precautions: • Are usually made into a peripheral vein with an angle of 15-20o. • A danger for IV rout is the introduction into toxic agents or microorganisms directly into bloodstream. • Solution must be sterile and free of particles or air bubbles (embolism).
Intramuscular injection Administration and precautions: • Slower onset of action and longer duration (depot effect) compared to IV route. • Are given in the upper outer portion of the iliac muscle (avoid nerve insertion). • Injection is administered with 90 o angle. • Volume of injection up to 5 mL.
Subcutaneous injection Administration and precautions: • Longer duration of action compared to IV and IM • Is given below the skin into the subcutaneous fat (45o angle). • Usually on the outside of the upper arm, may also in the abdomen. • No more than 1.5 mL should be injected. • Common example is insulin.
Intradermal injection Administration and precautions: • Administered into the capillary rich dermis (10-15o angle). • Used for local anesthesia. • The major use is allergy skin testing.
Rectal administration Drugs are administrated into the rectum in the from of suppositories or retention enema. Advantages: • Rapid onset of action. • Suitable for drugs destroyed by gastric acid. • Drugs subjected to first pass metabolism. • Suitable in case of nausea, vomiting and coma. Disadvantages: Irregular absorption.
Inhalation • Drugs may be inhaled to produce a systemic effect or a local effect on the respiratory tract. • Drugs are gases or volatile liquids. Advantages: • Rapid onset of action. • Can be used for a local effect on the lungs e.g. bronchodilator in asthma and bronchitis. or for a systemic effect e.g. inhalation general anesthetics.
Topical administration • The drug is applied to the skin or mucous membranes. • Used in treating localized disorders such as skin infections and nasal congestion. • Available in a variety of forms such as creams, lotions and eye and ear drops.
Advantages: • It is easier to control the effects of drugs applied locally and to produce the maximum benefit with minimum side effects. Disadvantages: • Slow onset of action.
Slow-release preparations • They are formulated to release their active drug slowly over a given period of time. • Used when it is necessary to control the release of small amounts of drug into body. • Present in the form of depot injections, transdermal patches, implants, tablets and capsules.
