Pharmacology 1 PDF

Dr Dina Hamdy Selim  Is the systematic naming of drugs, especially pharmaceutical drugs In the majority of circumstances, drugs have 3 types of names: Chemical Names, the most important of which is the IUPAC ( International Union of Pure and Applied Chemistry) name. Generic or Nonprop...

Dr Dina Hamdy Selim  Is the systematic naming of drugs, especially pharmaceutical drugs In the majority of circumstances, drugs have 3 types of names: Chemical Names, the most important of which is the IUPAC ( International Union of Pure and Applied Chemistry) name. Generic or Nonproprietary Names, the most important of which are international nonproprietary names(INNs) Trade Names ,brand name (proprietary name) , which are brand names.  Source of drugs 1. Plants: such as digitalis, vincristine. 2. Human and animals: such as epinphrine, insulin and adrenocoticotrpoic hormone. 3. Minirals: as iron, iodine and zinc 4. Synthetic and chemical substance: as sodium bicarbonate  Oral Parentral Intravenous Subcutaneous Intramuscular Sublingual Pulmonary (inhalation) Rectal Transdermal Topical (skin, eye, mucous membrane) Advantages: Oral ingestion is the most common method of drug administration. Most convenient route for most drugs. Safe Toxicities and/or overdose of oral drugs may be overcome with antidotes, such as activated charcoal. Disadvantages: Drugs not suitable for oral administration: Highly hydrophilic Low gastric pH inactivates some drugs. Subject to extensive first-pass effect. First-pass effect: drug undergoes metabolism before systemic absorption A. Intravenous(I.V.) IV injection is the most common parenteral route It is useful for drugs that are not absorbed orally , such as the neuromuscular blocker pancuronium. Advantages: Rapid action Delivered in the desired amount Irritant drugs given I.V. not S.C. Inemergency therapy and when a patient is unconscious ,uncooperative, or unable to retain anything given by mouth ,parenteral therapy may be anecessity. Disadvantages: Increased risk of adverse effects. Need monitoring to the patient. Difficult for patients to perform the injections them selves if self-medication is necessary.  SC injection provides absorption vi a simple diffusion and is slower than the IV route. The rate of absorption following subcutaneous injection of a drug often is sufficiently constant and slow to provide a sustained effect. Absorption of drugs implanted under the skin in a solid pellet form occurs slowly over a period of weeks or months ;some hormones(e.g.,contraceptives) are administered effectively in this manner. Injection into a subcutaneous site can be done only with drugs that are not irritating to tissue ;otherwise ,severe pain,necrosis may occur. Cannot inject large volume. Drugs commonly administered via the subcutaneous route include insulin and heparin.  Drugs administered IM can be in aqueous solutions ,which are absorbed rapidly, or in specialized depot preparations, which are absorbed slowly. Depot preparations often consist of a suspension of the drug in a non aqueous vehicle such as polyethylene glycol. The drug then dissolves slowly, providing a sustained dose over an extended period of time. Suitable for oily vehicle and irritant substances. BBB slows the entrance of drugs into the CNS local and rapid effects of drugs on the meninges or cerebrospinal axis are desired, as in spinal anesthesia Brain tumors or serious CNS infections also may be treated by direct intracerebroventricular drug administration  Beneath the epidermis, within the dermal The usual site for intradermal injection is the anterior forearm Volume of solution administered intradermally is limited to 0.1 ml. Slow onset of action and the rate of absorption used for diagnostic agents, desensitization, testing for potential allergies, or immunization. 3. Sublingual & Buccal Administration Placement under the tongue allows a drug to diffuse in to the capillary net work and enter the systemic circulation directly. Advantages: Ease of administration Rapid absorption By pass of the GIT environment e.g. nitroglycerine 4.Rectal Administration This route is also use fulif the drug induces vomiting when given orally,if the patient is already vomiting, or if the patient is unconscious. The rectal route has the additional advantage of preventing destruction of the drug in the GI environment. Absorption is often irregular and incomplete and may cause irritation to the rectal mucosa.  This route of administration achieves systemic effects by application of drugs to the skin,usually via a transdermal patch. The rate of absorption can vary markedly ,depending on the physical characteristics of the skin at the site of application, as well as the lipid solubility of the drug. Transdermal This route is most often used for the sustained delivery of drugs. Examples:Antianginal drug (nitroglycerin), Antiemetics,Nicotine transdermal patches, which are used to facilitate smoking cessation  Systemic effect: Rapid due to large surface area e.g. volatile anethetics Local effect (earosols) Bronchodilators (e.g. salbutamol) What is dosage form? ▪It is the final marketed pharmaceutical products containing the active drug. ▪It contains the drug + non-active components (excipients) for diluting or solubilizing the drug (e.g. bulking ,binder, sweetener, preservatives ). ▪These dosage forms may be: (classification according to physical form) o Solid: Tablets, capsules, sachets, suppositories o Liquid: Syrup, emulsion, parental fluids, sprays o Semi-solid: Ointment, creams 1. Oral Dosage Forms Oral dosage forms are those taken by mouth They include: Capsules, tablets, lozenges, sachets containing powders (to be dissolved or suspended),syrups , suspensions, and emulsions. Capsules 1. Hard gelatin containing powder 2. Soft gelatin containing liquid Lozenges Small medicinal tablet intended to be dissolved slowly in the mouth Taken for sore throats.  Tablets Regular tablet (film coated or sugar coated). Enteric coated tablet coated with material that delays release of the medication until after it leaves the stomach because the drug is irritant to stomach or decompose in acid pH. Enteric coatings are useful also for presenting a drug to sites of action in the ileum and colon. Effervescent tablet are large tablet that are dissolved in water before being taken. Sublingual tablet one that dissolves when held beneath the tongue,permitting direct absorption of the active ingredient by the oral mucosa. Chewable tablet one that we chew in our mouth be fore swallowing it to release their content  Liquids Solution where soluble drugs are dissolved in sugary solution (Syrup). Suspension where insoluble drugs are suspended in viscus medium. Emulsion where oily drugs are emulsified to give some thing like milk. Sachets A small bag containing powder drug to be swallowed as it is or dissolved in water first.  This time varies for different types of routes of administrations. Onset of action of different routes is as follows: Intravenous 30-60 seconds Inhalation 2-3 minutes Sublingual 3-5 minutes Intramuscular 10-20 minutes Subcutaneous 15-30 minutes Rectal 5-30 minutes Oral 30-90 minutes Topical/transdermal (topical) variable (minutes to hours). 24  Drugs possess more than one effect on the body. Indications :Approved for uses to treat conditions for which the drug has been proved to be effective Off-label: uses for which the drug has shown effectiveness but is not the approved use. Contraindications: Circumstances under which a drug should not be administered Side effects : Mild, undesirable effects of a drug, even at recommended dose Adverse or toxic effects :Drug effects that are dangerous, cause significant tissue damage, or are life-threatening Various Routes for Drug Administrations