COURSE BOOK
Subject: NURSING PHARMACOLOGY
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INTERNAL CIRCULATION
INDEX
Page Contents
Lesson 1: GENERAL INFORMATION ABOUT PHARMACOLOGY 1
Lesson 2: SEDANTIC AND HYPERTITIC DRUGS, EFFECTS ON THE CENTRAL NERVOUS SYSTEM 6
Lesson 3: DRUGS AFFECTING THE VEGETARIAN NERVOUS SYSTEM 11
Lesson 4: Antibiotics 17
Lesson 5: Anti-tuberculosis drugs - antiseptics 28
Lesson 6: Malaria treatment drugs 33
Lesson 7: Cardiac drugs - Diuretics 40
Lesson 8: Medicines for regulating digestive disorders - Anti-worm medicine 47
Lesson 9: H1 antihistamines, antipyretics - analgesics - anti-inflammatory drugs, morphine-type analgesics 58
Lesson 10. STEROID ANTI-INFLAMMATORY DRUGS (GLUCOSECORTICOIDS) 69
Lesson 11. USING SPECIALIZED MEDICINE 82
LESSON 12: Vitamins, major electrolytes and infusion fluids 85
LESSON 13. REGULATIONS ON POISONOUS DRUGS, ADDICTIVE DRUGS, PSYCHOTROPIC DRUGS, DRUG LABELS 89
Lesson 1: GENERAL INFORMATION ABOUT PHARMACOLOGY
Target:
Describe the pharmacokinetic processes of drugs. Analyze some characteristics of drug administration routes.
1.1. GENERAL
Pharmacology, in rhetoric, is the science of drugs. But to avoid the overly broad meaning of this word, Pharmacology only includes all studies on the interactions of drugs with biological systems. Drugs are substances or compounds that have the effect of treating or preventing diseases in humans and animals, or used in clinical diagnosis, used to restore and regulate the functions of organs in the body. Drugs can originate from plants, animals, minerals, metals or from semi-synthetic or chemically synthesized substances. First, drugs must be studied on experimental animals to determine their effects, mechanism of action, toxicity, therapeutic dose, toxic dose, mutagenic, teratogenic, carcinogenic effects... that is the subject of Experimental Pharmacology. These studies aim to ensure maximum safety for drug users. Only after there is enough reliable experimental data on animals can they be applied to humans. However, animals do not react to drugs exactly the same as humans; therefore, after the experimental phase on animals, drugs must be tested on groups of volunteers, on groups of patients at different facilities, compared with groups using classic drugs, in order to re-evaluate the effects encountered in the experiment and at the same time detect new symptoms, especially unwanted effects that have not been seen or cannot be seen in animals. These studies are the goal of Clinical Pharmacology. Pharmacology is always based on the latest achievements of related sciences such as physiology, biochemistry, biology, genetics... to increasingly understand the molecular mechanism of drugs, helping to research and produce new drugs that are increasingly specific, constantly improving treatment effectiveness. Pharmacology is also divided into: Pharmacodynamics studies the effects of drugs on living organisms. Each drug, depending on the dose, will have an early, specific effect on a tissue, an organ or a system of the body, used to treat a disease, called the main effect. In addition, each drug can also have many other effects, not used for treatment, but on the contrary, cause trouble for the user, called side effects, unwanted effects. All of these effects are the subject of research in Pharmacodynamics. Pharmacokinetics studies the effects of the body on drugs, which are the kinetics of drug absorption, distribution, metabolism and excretion.
Chronopharmacology studies the influence of circadian rhythms during the day and year on the effects of
The physiological activities of humans and animals are clearly affected by changes in the living environment such as light, temperature, humidity, etc. These activities change rhythmically and periodically, called biological rhythms. The effects of drugs can also change according to this rhythm.
Pharmacogenetics studies changes in individual, family, or racial drug sensitivity due to genetic causes. Pharmacogenetics is the intersection of Pharmacology - Genetics - Biochemistry and Pharmacokinetics.
Pharmacovigilance is the systematic collection and evaluation of adverse drug reactions associated with the use of drugs in the population. Adverse drug reactions are unwanted reactions that occur accidentally with doses of drugs used for the prophylaxis, diagnosis, or treatment of disease.
1.2. CONCEPTS
1.2.1. Absorption:
Absorption is the movement of a drug from the site of administration (oral, injection) into the bloodstream and then throughout the body to the site of action. Common routes of administration:
Through the digestive tract:
The advantage is that it is easy to use because it is a natural absorption route.
The disadvantage is that it is destroyed by digestive enzymes or the drug forms complexes with food, slowing down absorption. Sometimes the drug irritates the digestive mucosa, causing inflammation and ulcers.
Through the oral mucosa (sublingual medication): Because the medication enters the circulatory system directly, it is not destroyed by gastric juice and is not metabolized through the liver the first time.
Oral medication: The medication will pass through the stomach and intestines with the following characteristics:
In the stomach: pH = 1 - 3, so only weak acids that are less ionized, such as aspirin, phenylbutazone, and barbiturates, are absorbed. In general, absorption is low because the mucosa has few blood vessels and contains a lot of cholesterol, and the time the drug stays in the stomach is not long. Absorption is faster when hungry, but is easily stimulated.
In the small intestine: The main site of absorption.
Rectal suppositories: When oral administration is not possible, there is a suppository form.
Injections
Subcutaneous injection: because there are many sensory nerve fibers, it is painful, and because there are few blood vessels, the drug is absorbed slowly. Intramuscular injection: overcomes the two disadvantages of subcutaneous injection - some drugs that can cause muscle necrosis, such as calcium chloride, cannot be injected intramuscularly.
Intravenous injection: the drug is absorbed quickly, completely, and the dose can be adjusted quickly. Used to inject aqueous solutions or irritants that cannot be injected intramuscularly because the blood vessels are less sensitive and the blood dilutes the drug quickly if injected slowly. The drug is soluble in oil, the drug precipitates the components of the drug.
Blood or hemolysate should not be injected into the bloodstream.
Topical
Penetration through mucous membranes: the drug can be applied or dropped into the nasal, throat, vaginal, and bladder mucosa for local treatment.
Through the skin: few drugs can penetrate intact skin.
Eye drops: mainly have a local effect. When the drug flows through the nasolacrimal duct to the nasal mucosa, the drug can be absorbed directly into the blood, causing unwanted effects.
Other roads
Through the lungs: gases and volatile drugs can be absorbed through alveolar epithelial cells, the respiratory tract mucosa. Some drugs can be used in the form of mist for local treatment.
Spinal injection: usually injected into the subarachnoid or epidural space for low regional anesthesia.
Pharmacokinetic parameters of absorption: bioavailability (F)
Definition: Bioavailability F (bioavailability) is the percentage of the drug that enters the circulation in its active form and the rate of drug absorption compared to the dose administered. Bioavailability reflects drug absorption.
Meaning: When changing the excipients, the drug formulation will change the drug's solubility and change the drug's F. Thus, two formulations of the same product can have two different bioavailabilities.
1.2.2. Distribution
After being absorbed into the blood, a part of the drug will bind to plasma proteins, the free drug that is not bound to proteins will pass through the vascular wall to be transferred to the tissues, to the site of action, to the storage tissue or be metabolized and then excreted. The drug distribution process depends a lot on the regional circulation. Two types of factors affect the distribution of drugs in the body: On the body side (cell membrane properties, capillary membrane, number of drug binding sites and pH of the environment); on the drug side (molecular weight, solubility in water and lipid, acidity or base, ionization, affinity of the drug to the receptor).
Drug binding to plasma proteins: most of them bind to plasma albumin (weak acid drugs) and to a 1 glycoprotein (weak base drugs) in a reversible manner. The binding rate depends on the affinity of each drug to plasma proteins. Drug binding to plasma proteins depends on 3 factors: (1) The number of drug binding sites on plasma proteins; (2) Molecular concentration of drug-binding proteins; (3) Drug binding constant or drug binding affinity constant. Drug binding to plasma proteins makes absorption easier and excretion slower because blood protein is high, so at the site of absorption, the drug will be quickly pulled into the blood vessels. Plasma proteins are buffers, drug storage tanks, after binding
The drug will slowly release the drug into its free form and only the free form can pass through biological membranes to exert its pharmacological effect. The concentration of free drug in plasma and outside the interstitial fluid is always in a state of equilibrium. When the concentration of drug in the interstitial fluid decreases, the drug in the plasma will go out, the drug-binding protein will release the drug to maintain equilibrium. Many drugs can bind to the same site of plasma protein, causing competition, depending on the affinity of the drug. Drugs pushed out of the protein will increase the effect, possibly causing toxicity. In treatment, initially use an attack dose to saturate the binding sites, then give a maintenance dose to stabilize the effect. In pathological cases that increase or decrease the amount of plasma protein (such as malnutrition, cirrhosis, nephrosis, the elderly...), the drug dose needs to be adjusted.
Redistribution: Common with lipid-soluble drugs that act on the central nervous system and are administered intravenously.
Special distributions: Transport of drugs into the central nervous system, transport of drugs across the placenta.
Drug accumulation: Some drugs or toxins bind very tightly to certain tissues in the body and are retained for a long time, months to decades after the drug is used, sometimes only once. Some drugs accumulate in skeletal muscle and other tissue cells at higher concentrations than in the blood.
1.2.3. Drug metabolism
The purpose of drug metabolism: To eliminate foreign substances (drugs) from the body. To eliminate them, the body must metabolize these drugs so that they become polar complexes, easily ionized, thus becoming less soluble in lipids, difficult to attach to proteins, difficult to penetrate cells, and therefore more soluble in water, easily eliminated (through the kidneys, through feces).
Metabolic sites and major enzymes catalyzing metabolism:
Intestinal mucosa: protease, lipase, decarboxylase Serum: esterase
Lungs: oxidase
Gut bacteria: reductase, decarboxylase
Central nervous system: monoamine oxidase, decarboxylase
Liver: is the main site of metabolism, containing most of the enzymes involved in drug metabolism.
Factors that change the rate of drug metabolism
Age: Newborns lack many drug-metabolizing enzymes, and in the elderly, enzymes also age.
Hereditary
Exogenous factors: Metabolic enzyme inducers: have the effect of increasing the production of enzymes in the
Liver microsomes, increasing the activity of these enzymes. Metabolic enzyme inhibitors: some other drugs such as chloramphenicol, dicumarol, isoniazid, quinine, cimetidine... have an inhibitory effect, reducing the drug-metabolizing activity of enzymes, thereby increasing the effect of the combined drug.
Pathological factors: Diseases that damage liver function will reduce the liver's drug metabolism, easily increasing the effects or toxicity of drugs metabolized through the liver. Diseases that reduce blood flow to the liver such as heart failure or long-term use of beta-adrenergic blockers will reduce the liver's extraction coefficient, prolonging the half-life of drugs with high extraction coefficients in the liver.
1.2.4. Excretion: The drug is excreted in its original or metabolized form.
Renal excretion: This is the most important excretion route for water-soluble drugs with molecular weights less than 300.
Elimination process
+ Passive filtration through the glomerulus: free drug form, not bound to plasma proteins.
+ Active secretion through renal tubules: because there must be transport substances, there is competition for excretion. Active secretion occurs mainly in the proximal tubule, which has two different transport systems, one for anions and one for cations.
+ Passive diffusion through the renal tubules: a portion of the drug initially excreted in the urine is reabsorbed into the blood.
Excretion through the bile: After being metabolized in the liver, the metabolites will be excreted through the bile to be excreted in the feces. Most of them, after being further metabolized in the intestine, will be reabsorbed into the blood for excretion through the kidneys. Some glucuronide metabolites of drugs with a molecular weight of over 300 after being excreted through the bile into the intestine can be hydrolyzed by β-glycuronidase and then reabsorbed back to the liver through the portal vein to return to the circulation, called enterohepatic cycle drugs. These drugs accumulate in the body, prolonging the effect (morphine, tetracycline, cardiac digitalis...).
Excretion through the lungs: Volatile substances such as alcohol, essential oils; gases (nitrogen oxide, halothane). Excretion through milk: Substances that are highly soluble in lipids (barbiturates, non-steroidal anti-inflammatory drugs, tetracyclines, alkaloids), with molecular weights below 200, are easily excreted through milk. Because milk has a slightly more acidic pH than plasma, drugs that are weak bases may have slightly higher concentrations in milk than in plasma, and drugs that are weak acids may have lower concentrations.
Excretion through other routes: The drug can also be excreted through sweat, tears, keratinocytes (hair, nails), and salivary glands.
Lesson 2: Sedatives, Hypnotic Drugs, Effects on the Central Nervous System
Target:
Presents indications and contraindications of some sedatives, hypnotics, and central nervous system drugs.
Follow instructions for using sedatives, hypnotics, and central nervous system drugs.
2.1. ANESTHETICS
2.1.1. GENERAL ISSUES
Definition: Anesthetics cause loss of sensation (pain, temperature) in an area of the body, at the site of application, while motor function is not affected.
Characteristics of a good anesthetic: Many drugs have anesthetic effects, but a good anesthetic needs to meet the following standards:
Completely and specifically blocks sensory transmission.
After the drug's effects, nerve function was completely restored.
Short onset time, suitable duration of action (usually about 60 minutes). Non-toxic, non-irritating to tissue and non-allergenic.
Soluble in water, stable in solution, still active after sterilization.
Pharmacological effects:
Local effects: Anesthetics act on all central nerve fibers (sensory, motor) and autonomic nerves, from small fibers to large fibers depending on the concentration of the drug. The order of loss of sensation is pain, cold, heat, superficial touch, then deep touch. When the drug wears off, the effect recovers in the opposite direction. Depending on the clinical purpose, different routes of drug administration are used:
+ Surface anesthesia: apply or infuse local medication (0.4 - 4%).
+ Infiltration anesthesia by subcutaneous injection so that the drug can penetrate into the nerve endings (0.1 - 1% solution).
+ Conduction anesthesia: injecting drugs into the nerve conduction pathway (nerve trunk anesthesia, ganglion blockade, epidural anesthesia, spinal anesthesia).
Systemic effects: Only appear when the anesthetic penetrates the circulation at effective concentrations.
Uses: The central nervous system inhibitory effect appears earliest with the inhibitory center, causing signs of stimulation: restlessness, anxiety, muscle tremors, convulsions (treated with diazepam), disorientation.