Drugs affecting the Respiratory Drugs affecting the Respiratory SystemsSystems

Kuntarti, SKp, MBiomed

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Anatomy & Physiology of Anatomy & Physiology of respiratoryrespiratory1. The Upper respiratory tract

⇒ nares, nasal cavity, pharynx,& larynx

2. The Lower respiratory tract⇒ trachea, bronchi, bronchioles, alveoli, & alveolar-capillary membrane

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Ventilation & RespirationVentilation & Respiration� Ventilation

⇒ is the movement of air from the atmosphere through the upper & lower airways to the alveoli

� Respiration⇒ the process whereby gas exchange occurs at the alveolar-capillary membrane

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Phases of respirationPhases of respiration1. Ventilation

⇒ in which oxygen passes through the airways

2. Perfusion⇒ in which blood from the pulmonary circulation is

adequate at the alveolar-capillary bed

3. Diffusion of gases⇒ in which oxygen passes into the capillary bed to be circulated and carbon dioxide leaves the capillary bed & diffuses into the alveoli for ventilatory excretion

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Lung compliance1. Connective tissue (collagen & elastin)2. Surface tension in the alveoli (by surfactant)

Control of respiration� Chemoreceptors → changes of concentration of O2,

CO2, H+

* The central chemoreceptors: in the medulla near the respiratory center & cerebrospinal fluid (by: ↑ CO2 & ↓ pH)

* Peripheral chemoreceptors: in the carotid & aortic bodies (by: changes of oxygen levels)

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Bronchial smooth muscle� Contraction → constricts the airway

* The vagus nerve (parasympathetic nervous system) → acetylcholine → bronchoconstriction

* The sympathetic nervous system → epinephrine → bronchodilatation

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Common manifestations of respiratory disease� Sneeze

- caused by a foreign body or irritant; inflammation- the early stages of a ‘cold’- requires no medication; a steroidal nasal spray for

prophylactic- Sodium cromoglycate for prophylactically in the control

of allergic rhinitis by topical inhalation (Hopkins, 1992)

�� SputumSputum- purulent (by infection); frothy (by pulmonary edema); bloodstained (by haemoptysis); tenacious (by cystic fibrosis or mucous plugging)

- Expectorants to liquefy mucus

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Common manifestations of respiratory disease� Noisy breathing

- Stridor is a rasping sound heard predominantly in inspiration

- a cough that is caused by inflammation of the mucosa of the larynx, trachea, & bronchi, with narrowing of the subglottic area (by virus)

- Medication: moist inhalations, nebulized steroids & adrenalin

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Drugs affecting the Respiratory Drugs affecting the Respiratory SystemsSystems� Drugs for asthma

1. anti-inflammatory agents2. bronchodilators

� Drugs for rhinitis, cough, & colds1. nasal decongestans2. antihistamines3. anti-inflammatory agents4. antitussives5. Expectorants & mucolytics

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Asthma

� common in children & adults

� characteristic signs: breathlessness, tightness in chest, wheezing, dyspnea, & cough

� chronic inflammatory disorder of the airway � a reaction to allergens

� symptoms of asthma: combination of inflammation & bronchoconstriction

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Drugs for asthma2 main pharmacologic class:1. Anti-inflammatory agents: glucocorticoids &

cromolyn2. Bronchodilators: beta2 agonists

� most antiasthmatic drugs can be administered by inhalation, caused:- therapeutic effects are enhanced (by delivering drugs directly to their site of action)- systemic effects are minimized- relief of acute attacks is rapid

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Bronchodilator & antiasthma� Sympathomimetics/Beta2-Adrenergic agonist

- Examples: epinephrine, isoproterenol, isoetharine, albuterol, terbutaline, ephedrine

- Use/ mechanism of action: treat asthma, bronchitis, & emphysema by stimulating beta2 receptors in bronchial smooth muscle to produce bronchodilatation, & thereby relieve bronchospasm

- Adverse effect:CNS: restlessness, anxiety, dizziness,headache, insomnia; Cardiovascular: palpitations, cardiac arrhythmias, tachycardia, hypertension, cerebrovascular accidents, angina; GI: nausea, severe vomiting, diarrhea

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Sympathomimetics

� Adverse effect:Skin: local necrosis & tissue sloughing from extravasated intravenous catecholamines

� Contraindication:cardiovascular diseases, phenochromacytoma, hypertension

� Precaution: hyperthyroidism, diabetes, & pregnancy

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Glucocorticoids (steroid)

� Examples: dexamethasone, betamethasone, prednison

� Use/mechanism of action: steroids reduce symptoms of asthma by suppressing inflammation (decreased synthesis & release of inflammatory mediators; decreased infiltration & activity of inflammatory cells; decreased edema of the airway mucosa)

� Adverse effect: inhalation� oropharingeal candidiasis & dysphonia (hoarseness & speaking difficulty); oral (in prolonged therapy �adrenal suppression, osteoporosis, hyperglycemia, peptic ulcer disease, & suppression of growth (in young patients)

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Glucocorticoid

� Contraindication: systemic fungal infections; individuals receiving live-virus vaccines

� Cautions: pediatric, pregnant & breast feeding woman

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Cromolyn/ Mast cell stabilizers

� Examples: Cromolyn, Nedocromyl� Use/ mechanism of action: Cromolyn suppresses

inflamation by stabilizing the cytoplasmicmembrane of mast cells, thereby preventing release of histamine & other mediators. Cromolyninhibits eosinophils, macrophages & other inflammatory cells

� Adverse effects: cromolyn is the safest of all antiasthmatic medications, the most common reactions are wheezing, coughing & unpleasenttaste

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Methylxanthines� Examples: Theophylline, aminophylline,

dyphylline

� Use/ mechanism of action: theophylline produces bronchodilatation by relaxing smooth muscle of the bronchi, the most probable mechanism is blockade of receptors for adenosine.

� Adverse effects: theophylline has a narrow therapeutic range, & hence dosage must be carefully controlled; at plasma levels > 20µg/ml : nausea, vomiting, diarrhea, insomnia, restlesness, dysrhythmia & convulsion

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Anticholinergic/ muscarinic antagonist

� Examples: atropine, ipatropium bromide (atrovent)

� Use/ mechanism of action: by blocking muscarinic cholinergic receptors in bronchi, & thereby promotes bronchodilatation

� Adverse effects: dryness of oropharynx, cough

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Drugs for rhinitis� Rhinitis: an inflammation of the nasal

mucous membranes� Symptoms: sneezing, rhinorrhea, nasal

itching, & nasal congestion� Allergic & non-allergic� Drugs: (1) nasal decongestants (2)

antihistamines (3) intranasal anti-inflammatory

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Nasal decongestants� Examples: phenylephrine, phenylpropanilamine (ppa)� Use/ mechanism of action: by stimulating alpha1-

adrenergic receptors on smooth muscle of nasal blood vessels � vasocontriction� shrinkage of swollen membranes� nasal drainage; topical administration more rapid & intense than oral administration

� Adverse effects: rebound congestion; CNS stimulation; cardiovascular effects� widespread casoconstriction

� Contraindication & caution: hypertension & CAD

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Antihistamines (H1-receptor antagonist)

� Examples: diphenhydramine, chlorpheniramine, promethazine, azatadine (1st generation), terfenadine, astemizole, loratadine (2nd generation)

� Use/ mechanism of actions: these agents can relieve sneezing, rhinorrhea, & nasal itching by blocking H1 receptor & thereby preventing the actions histamines at these sites

� Adverse effects: sedation (1st generation), cardiac dysrytmia, dizzines, nausea, vomiting,constipation, dry mouth

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Drugs for cough & cold

� Cough: a complex reflex involving the central & pheripheral nerve systems & muscles of respiration can be initiated by irritation of the bronchial mucosa

� (+): remove foreign matter & excess secretions from the bronchial tree

� (-): deprive us of comfort & sleep

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� Common cold: an acute upper respiratory infection of viral origin

� Symptoms: rhinorrhea, sneezing, cough, sore throat, headache, malaise,& myalgia

� Combination cold remedias, 2 or more of:1. nasal decongestants2. antitussives3. analgesic4. antihistamines5. caffeine

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Antitussive agents� Examples: opioid � codeine, hydrocodone; non-

opioid� dextromethorpan hydrobromide (DMP)

� Use/ mechanism of action: suppress coughing by altering response threshold of cough center in the medulla or peripherally by inhibiting pulmonary stretch, thus decreasing impulses to the cough center

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Antitussive agentsAntitussive agents� Adverse effects:

- Codeine: impaired alertness or coordination, hypersensitivity, dependence; toxic reactions: euphoria, hyperactivity, nystagmus, uncoordinated movements, stupor, shallow breathing- DMP: drowsiness & GI upset; toxic reaction: miosis, bradycardia, tachycardia, hypotension, narcosis, seizures, circulatory collapse

� Contraindication: pregnancy, lactation, known hypersensitivity

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Antitussive agentsAntitussive agents� Precautions: benign prostatic hypertrophy, debilitation,

thoracotomy, laparotomy, history of drug abuse

� Drug interactions: - DMP and MAO (monoamine oxidase) inhibitors: excitation, hyperpyrexia

- narcotic/opioid antitussive with MAO inhibitors, alcohol, & other CNS depressants: potentiation of CNS depressive effects

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Expectorants agentsExpectorants agents� Examples: ammonium chloride, guaifenesin/glyceryl

guaiacolate (GG)

� Use/ mechanism of action:facilitate expulsion of mucus by reducing adhesiveness and surface tension of mucus

� Precaution:liver and renal insufficiency

� Adverse effects: - GG: drowsiness, nausea, vomiting

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Mucolytic agentsMucolytic agents� Examples: bromhexin, ambroxol, acetilcistein,

hypertonic saline

� Use/ mechanism of action: enhance mucolysis by altering molecular composition of mucus, reducing viscosity; ambroxol: stimulate surfactant production of premature infant with respiratory distress syndromes

� Precaution: gastric ulcer

� Adverse effects: - bromhexin: nausea, ↑ serum transaminase level- acetilcistein: bronchial spasm, nausea, vomiting,

stomatitis, haemoptysis

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Nursing diagnosis1. Ineffective airway clearance related to

mucus accumulation manifested by cough & ronchi

2. Risk for infection related to build up of respiratory secretions

3. Risk for injury related to CNS depression

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Nursing implementationNursing implementation� Administration procedures

* Increase fluid intake of client taking expectorant

� Daily monitoring & measurements* Monitor client taking codeine for signs of respiratory depression

� Client teaching1. Explain to client the importance of increasing fluid intake when

taking expectorant2. Encourage patient who is confined to bed and taking expectorant to

turn, breathe deeply, & cough every 2 hours3. Warn client taking a narcotic antitussive not to drink alcohol4. Caution client that prolonged use of codeine may cause

dependence5. Show client how to use and clean nebulizer for acetylcystein

administration

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Nursing evaluationClient shows:

� Absence of coughing.

� Improved ability to cough up mucus.

� No signs or symptoms of infection (Cardinal signs).

� No signs of excessive CNS depression.

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