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Beta – adrenergic blocking drugs

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Beta – adrenergic blocking drugs Powered By Docstoc
					‫نمىذج إجابة علم األدوية‬
2008 ‫يناير‬

‫جامعة بنها كلية التمريض‬ ‫للفرقة الثانية‬ ‫دور‬

1- Beta – adrenergic blocking drugs
The are competitive inhibitors of catecholamine binding at beta – adrenergic receptors. 1- cardioselective beta-blockers: e.g acebutolol. These drugs block selectively cardiac adrencoeptors, therefore they may be safer in obstructive airways diseases, peripheral vascular diseases and diabetes mellitus. 2- noncardioselective oxprenolol, and nadolol. These drugs block adrenoceptors in the heart and other tissues. beta-blockers: e.g propranolol, pindolol, Atenolol, Metoprolol, and

Effects of beta-blockers:
- CVS: Reduction of exercise-and anxiety-induced tachycardia, decrease contractility of the heart, and reduction in blood pressure. - Respiratory system: Bronchoconstriction in asthmatics. - Metabolism: Hypoglycaemia. - CNS: Centrally mediated hypotension. - Peripheral nervous system: Reduction of tremor (e.g due to anxiety, thyrotoxicoses, and hypoglycaemia).

Uses of beta-blockers:
Hypertension, angina, arrhythmias, post-myocardial Infarction, anxiety, migraine prophylaxis, essential tremor, and open angle glaucoma (Timolol eye drops – probabl y decrease aqueous humour formation).

Contraindications to beta-blockers:
Heart failure, heart block, peripheral vascular diseases, bronchial asthma, emphysema, chronic Bronchitis, and diabetes mellitus.

2- Anticoagulants
1- Heparin: It acts as an antithrombin preventing the formation of fibrin formation of fibrin from fibrinogen. It acts immediately both in vitro and in vivo. Indications: - Haemodialysis - Acute arterial obstruction of a limb - Disseminated intravascular coagulation (DIC) - Deep vein thrombosis; thrombosis; pulmonary embolism Toxicity: - Spontaneous haemprrhage - Allergy - Osteoporosis - Alopecia - Thrombocytopenia

2- Oral anticoagulants
1- Coumarin derivatives: Dicoumarol, Warfarin,……. 2- Inadanedione derivatives: phenindione (Dindevan), diphenadione... Uses: - Prevention and treatment of deep venous thrombosis, pulmonary embolism, and postoperative thrombosis. - Acute arterial embolism: start with heparin and warfarin for maintenance

- Prevention of coronary thrombosis - Atrial fibrillation, artificial heart valves and pulmonary hypertension. Toxicity: - Heamorrhage - Allergic reactions - Whithdrawal may lead to thrombotic episodes - The lead to may drug interactions

Oral anticoagulant interactions:
1- Drugs enhance the anticoagulant effect: A- Cimetidine, phenylbutazone via inhibition of hepatic metabolism. B- Nonsteroidal anti-inflammatory drugs (NSAIDS) VIA reduction of platelet adhesion. C- Oral antibiotics via inhibition of vitamin K production by microorganisms in the gut D- Sulphonamide, phenytoin binding sites E- Clofibrate lowers plasma triglycerides which carry vitamin K 2- Drugs reduce the anticoagulant effect: A- Barbiturates, phenytion, Carbamazepin, glucocorticoids, and

rifampicin via enzyme induction B- Contraceptive pills increases synthesis of clotting factors C- Vitamin K allow activation of clotting factors

3- Bioavailability:
It is the amount of drug reaching the systemic circulation unchanged and pharmacologically effective. Factors affecting bioavailability: A- Factors affecting absorption of drugs from gastrointestinal tract (GIT). 1- molecular weight and lipid solubility of the drugs.

2- Rate of drug dissolution in GIT. 3- Food decreases absorption of some drugs. 4- GIT diseases decreases drug absorption. B- The first pass effect.

4- Pencillins
Mechanlsm: - They inhibit bacterial cell wall synthesls thay are bactericidal. Spectrum: - They act against gram (G) +ve coccl & bacill, g-ve cocci, spirochetes and actinomyces. Ampicillins are also effective against G-ve baclll. Indications: 1- Tonslllts 2- Endocarditis 3- Pneumpnla 4- Gonorrhea and syphills 5- Tetanus 6- Ampicclllins are also used in urinary tract infections and typhold fever. Side effects: 1- Allergy: Asthma and anaphylactic shock which is treated by adrenaline I.V and cortisone I.V 2- High doses cause CNS Irration 3- Nausea and vomiting. Preparations: 1- Benzyl penciiiin 2- Procalne penciiin 3- Benzathine penciiin: long acting penciiiin. 4- Amplciiin

5- DRUG Therapy OF PEPTIC ULCER
Drugs used in the treatment of peptic ulcer are: 1- Histamine H-2 receptor blockers: Cimetidine

2- Anticholinergic drugs: Atropine and pirenzepine. 3- Mucosal protective agents: sucralfate. 4- Antacids. H-2 receptor blockers They block H-2 receptors in the parietal cells of the stomach decreasing gastric acid secretion. Uses: 1- peptic ulcer. 2- Upper GIT bleeding. 3- Reflux esophagitis. Side effects: 1- Nausea and voiting. 2- Myalgia and fatigue. 3- Headache, confusion and hallucinations. 4- Gynecomastia in males. 5- Galactorrhea in females. Preparations: 1- Cimetidine (Tagamet). 2- Ranitidine (Zantac). Anticholinergic drugs - They Block muscarinic receptors in the parietal cells of the stomach, reducing gastric acid secretion. They also reduce gastric motility. - Side effects:

1- Dry mouth. 2- Constipation. 3- Urine retention. 4- Glaucoma. 5- Blurring of vision. 6- Tachycardia. Pirenzepine: It is a gastroprotective anticholinergic drug.

- It inhibits gastric acid secretion with minimal systemic side effects. - It is given oral before meals.

SUCRALFATE
- It is a mucosal protective agent. - It acts locally in the presence of acid, it combines with protein and mucous in the base of the ulcer forming a protective coat against acid and pepsin. - It is given oral before meals.

ANTACIDS
They neutralize gastric acidity. They are mainly used in cases of hyperacidity. Uses: 1- Duodenal ulcer. 2- Reflux esophagitis. Types of antacids: 1- Systemic antacids: NaHCO3. 2- Non systemic antacids: aluminum hydroxide, Maagnesium oxide and caco3. Side effects: 1- Calcium and aluminum antacids cause constipation.

2- Mangesium antacids causse diarrhea. 3- Systemic alkalosis with high doses of systemic antacids. 4- High sodium content of some antacids can harm the patients with cardiac, renal or hepatic disease.

6- Drugs Used in bronchial asthma:
1-Bronchodilator sympathomimetics include: A- Adrenaline: - It is an effective bronchi. - It is given by injection or inhalation in the treatment of acute bronchial asthma. - Its side effects are tachycardia, extrasystoles and rise of blood pressure. B- Isoprenaline: - It is a powerful bronchodilator (Baction). - It is given sublingual or by inhalation in arrhythmias. 2- Beta 2 agonists - Salbutamol (Ventolin): - It is a specific B2 agonist. - It produces bronchodilation with minimal cardiac side effects. - It is available as tablets, syrup and inhalation form. - Other beta 2 stimulants include terbutaline, fenoterol and riniterol - During attack, beta 2 stimulants given by inhaler.

Method of use of inhaler: 1- Before use shake canister 2- Place it in the mouth 3- Pre3ss to dispense a measured does of drug in the form of aerosol while patient inhales deeply

4- Patient keeps drug in the lung before exahalling - This may be repeated after 2 minutes - Inhaler is used 2-3 times a day

3- Direct bronchodilators include: Aminophllyine: - it is a powerful bronchodilator. - It is one of the most useful drugs used in the treatment of bronchial asthma. - It also stimulates heart, increases cardiac output and heart rate. - It causes diuresis - It is useful when asthma is resistant to adrenaline by restoring sensitivity to B-adrenergic agonists. - It is given orally, slowly IV and as suppositories. - Oral administration causes gastrointestinal irritation 4- Corticosteroids also given in bronchial asthma and may be given as inhalers e.g bechlome thasone (becotid) or betamethasone to inhibit antigen-antibody reaction that precipitates acute attack.

7- Digitalis glycosides
Digoxin and digitoxin most commonly used Uses: 1- fast atrial fibrillation 2- atrial flutter 3- supraventricular tachycardia 4- congestive heart failure (still controversial)

digitalis intoxication:
CVS: Bradycardia, paroxysmal atrial tachycardias, A-V block, premature ventricular contraction (PVC), ventricular fibrillation. GIT: Anorexia, nausea and vomiting CNS: headache, drowsiness, confusion and hallucination Vision: Blurred, White vision, diplopia and scotomata

Treatment of digitalis toxicity:
1- Stop digitalis administration 2- Stop diuretics that cause potassium depletion 3- Give potassium orally or by IV infusion 4- Treatment of arrhythmias by phenytoin, lignocaine or by beta blockers 5- Atropine con control bradycardia and A-V block. 6- Feb-fragment-digitalis antibodies

8- Source of insulin
567Bovine insulin: obtained from cattle Porcine insulin: obtained from pork Human insulin: obtained by genetic engineering.

The gene responsible for insulin synthesis is inserted in certain bacteria (E-coli) or Baker's yeast which will synthesize insulin. Uses: 1- Juvenile diabetes mellitus: It occurs in the young age and called insulin dependant diabetes mellitus (IDDM) 2- Non-insulin dependant diabetes mellitus (NIDDM): this type occurs in old age after 40 years. Insulin is used in this type when it is severe or it does not respond to oral drugs. 3- Diabetic ketoacidosis.

4- Diabetes mellitus with complications like infections, trauma, surgery and pregnancy. Side effects: 1- Hypooglycemia due to overdose. 2- Allergy: Urticaria and angioneurotic edema. 3- Resistance to insuline. 4- Llipodystrophy: Atrophy or hypertrophy of fat. Preparations: There are 3 types: 1- Rapid acting: regular (soluble) insulin. Give SC, at first 2-3 times before meals, then dose adjusted according to blood glucose level. Given IV in diabetic ketaoacidosis. It has rapid onset of action and short duration of action 2- Intermediate acting: I sophane insulin suspension (NPH). Given SC or IM. Onset of action: 1-2 hours. Duration: 16-24 hours. 3- Insulin-zinc suspensions - slow release preparations in which rate of release is controlled by changing particles size. - Given SC and include: a- Semilent or semitard insuline: onset: 1.5-2 hours. Duration: 12-16 hours b- Lent or monotard insulin: onset: 3 hours. Duration: 24-30 hours c- Ultralent or ultratard insulin: Onset: 5 hours. Duration: 30 – 36 hours d- Long actings: Protamine zinc insulin (PZI). Onset: 4 hours. Duration: 24: 36 hours.

‫أستاذ ــــور: محمود الفولي‬ ‫دكت‬ ‫ــــورة: نشوى ابورية‬ ‫دكت‬