Respiratory Drugs and the Autonomic Nervous System

Respiratory Drugs: Overview

• Medications that relax the muscles around the airways are called bronchodilators
• Beta-2 agonists, anticholinergics, and methylxanthines can facilitate bronchodilation
• Anti-inflammatory agents can help reduce inflammation in respiratory diseases and conditions
• Corticosteroids, Leukotriene modifiers, and mast cell stabilizers are examples of anti-inflammatory agents used
• Drugs are also used to address the symptoms of respiratory diseases
• Cough suppressants, expectorants and mucolytics are examples of drugs used to relieve respiratory disease symptoms

Types of Respiratory drugs and how they affect the autonomic nervous system

• Drugs can affect the autonomic nervous system, which can dilate or constrict the airways
• Sympathetic nervous system agonists like Adrenergic drugs stimulate dilation
• Sympathetic nervous system blockers like Adrenergic blockers inhibit dilation
• Parasympathetic nervous system stimulants like Cholinergic drugs constrict airway
• Parasympathetic nervous system inhibitors lile Anticholinergics dilate the airway

Nervous System

• Central Nervous System (CNS) comprises the brain and spinal cord
• Peripheral Nervous System (PNS) connects the CNS to the rest of the body
• Somatic nervous system allows voluntary control over skeletal muscles
• The autonomic nervous system controls smooth muscle, cardiac muscle, and glands involuntarily
• The sympathetic nervous system expends energy and is activated under stress
• The parasympathetic nervous system conserves energy and is activated under non-stressful conditions

Beta2-Adrenergic Agonists

• Beta2-adrenergic agonists are receptor agonists and used for respiratory benefit
• Such receptors found in smooth muscle of bronchi, gut, uterus, and blood vessels
• Activation of these receptors stimulates the sympathetic nervous system and results in a "fight or flight" response
• Indicated for stimulation of airway dilation and treating conditions like asthma and COPD
• Side effects include tachycardia, palpitations, arrhythmias, anxiety, and muscle tremors
• Short-acting beta2 adrenoceptor agonists (SABA) are effective for acute bronchospasm relief and first-line medications for acute asthma attacks
• Therapeutic duration lasts 3-6 hours and onset of action is under 5 minutes
• Examples include Salbutamol, Terbutaline sulfate
• Long-acting beta2-adrenoceptor agonists (LABA) are used with corticosteroids to prevent inflammation in chronic asthma
• Duration of action is 12 hours
• Examples include Salmeterol, Formoterol, Indacaterol

Anticholinergics

• They block acetylcholine binding to cholinergic receptors, blocking the parasympathetic nervous system, to mimic the fight or flight response
• It reduces smooth muscle tone in the respiratory tract
• Indicated to dilate the airway and treat bronchospasm
• Drawbacks include drowsiness, blurred vision, dry mouth, tachycardia, palpitations, constipation, and urinary retention

Anticholinergics - Types

• Short-acting antimuscarinics (SAMA) bronchodilators are alternatives to beta agonists in asthma therapy
• Use is dictated "as required" by symptoms and NOT on a regular basis
• Example of SAMA – Ipratropium Bromide
• Long-acting antimuscarinics (LAMA) are given on a regular basis to prevent or reduce symptoms
• The combination of LABA and LAMA can increase the effect of bronchodilation
• Inhalation route is preferable to oral drug administration
• Example of a LAMA – Tiotropium

Methylxanthines

• Methylxanthine inhibits intracellular calcium release, decreases microvascular leakage into the airway mucosa
• Results in bronchodilation
• Used for asthma and COPD but are less effective than beta agonists
• Carries more side effects
• Side events include headaches, vomiting, cardiac arrhythmias, seizures, and aggravation of gastroesophageal reflux
• Examples include Theophylline and Aminophylline
• Theophylline requires individualized dosing based on serum levels to calculate dose (target 5-15 mcg/ml)
• It is mainly used for long-term oral prophylaxis for asthma unresponsive to beta-agonists or inhaled corticosteroids
• Methylxanthine Theophylline helps manage nocturnal asthma

Corticosteroids, inhaled

• Steroids reduce inflammation and airway swelling, which eases breathing
• Considered 'preventers'
• It is indicated for asthma and COPD maintenance for long-term prophylaxis
• Common for advanced disease when combined with long-acting bronchodilator therapy
• Side effects like may interfere with normal flora balance, and induce oral candidiasis
• Nursing- Reduce number of pathogens in the mouth, prevent pulmonary infection

Corticosteroids - Oral + Intravenous

• Intravenous/oral steroids reduce inflammation, airway swelling and support breathing
• For short-term severe, acute exacerbations in the hospital for 5-7 days
• Side effects can include Cushing Syndrome, various others, risks may outweigh benefits
• PO Prednisolone/IV Hydrocortisone are key examples

Allergic Rhinitis

• Inflammation of the nasal mucosa due to exposure to allergens like pollens, dust mites etc requires genetic predisposition
• Immediate hypersensitivity occurs when antigen interacts with Immunoglobulin E (IgE)
• Antigen-specific IgE bound on mast cells cause release of histamine, cytokines, chemokines, and leukotrienes

Allergic Rhinitis: Histamine's Role

• Histamine acts on H1 receptors, increasing vascular permeability and vasodilation
• Fluid moves from capillaries into surrounding tissues, increasing swelling.
• Other effects: erythema, urticaria, skin rash/pruritus, running nose, sneezing and Increase smooth muscle contraction

Allergic Rhinitis - Antihistamines

• Antihistamines stop histamine acting on H1 receptors, decrease vascular permeability, and induce vasoconstriction
• They stop fluid moving from capillaries into surrounding tissue, decrease swelling
• H-1 receptor antihistamines have anticholinergic properties for allergies and asthmatic coughs
• Also serve in relieving allergic rhinitis, nasal congestion, stop running nose and are a type of antitussives

First-generation H1 antihistamines:

• Have anticholinergic properties, duration is around 4-6 hours
• Affect the central nervous system, cause dry mouth, blurred vision, reduce coordination
• Advised to be taken after food or with food and to avoid alcohol

First Generation Antihistamines - Examples

• Brompheniramine (BroveX CT®)
• Chlorpheniramine (Piriton, Ahist®,Aller-Chlor® and Chlor-Trimeton®)
• Clemastine (Dayhist®, Tavist Allergy®)
• Cyproheptadine (Periactin®).
• Dimenhydrinate (Dramamine®).
• Diphenhydramine (Alka-Seltzer Plus Allergy®, Benadryl® and Vicks ZzzQuil Nighttime Sleep-Aid®).
• Doxylamine (Unisom®).
• Hydroxyzine (Atarax®, Rezine® and Vistaril®)
• Promethazine (Phenergan)

Second Generation Antihistamines

• Duration action of antihistamine 12-24 hours
• S/E anticholinergic properties and blurred vision
• Selectively bind to peripheral histamine receptors and less drowsy
• Azelastine eye solution (Optivar®) and Azelastine nasal spray (Astelin®, Astepro®).
• Cetirizine (Zyrtec®).
• Desloratadine (Clarinex®).
• Fexofenadine (Allegra®), Loratadine (Claritin®)

Alpha 1 Adrenergic Agonists

• Alpha 1 Adrenergic Agonists (a1) activate receptors and stimulate sympathetic nervous system
• Results in fight or flight response and stimulate vasoconstriction for drying nasal secretions
• Indications used to inhibit salivation, reduce secretions and relieve nasal congestion
• Tachycardia, arrhythmias, pupil dilation, dry mouth are Side effects
• Examples – oral includes Ephedrine, Pseudoephedrine, Phenylephrine
• Nasal Spray includes Naphazoline, Oxymetazoline, Xylometazoline and Tetrahydrozoline

Antitussives: Promethazine Compound Linctus

• Antitussives are antitussive: Promethazine Compound Linctus compounds consist of codeine Phosphate, Ephedrine Hydrochloride, Promethazine Hydrochloride
• Codeine is an opioid that suppresses cough
• Ephedrine acts as agonist of alpha-1, beta-1 and beta-2-adrenergic receptors
• Ephedrine works by reducing swelling and constricting blood vessels to allow easier breathing

Antitussives

• Actified (Codeine Phosphate, Pseudoephedrine Hydrochloride, Triprolidine Hydrochloride)
• Codeine (Opioid to suppresses cough)
• Pseudoephedrine(Alpha, beta, for decongestion by vasoconstriction)
• Ephedrine (Derived from Ephedra plant)
• Triprolidine (Antihistamine for runny nose, itchy nose and eyes, sneezing and throat)

Antitussives: Action/Recommendations

• Action mechanism of Pholcodine that suppress cough by reducing dry cough
• Side reactions include dizziness, nausea, constipation and tachycardia and dependence
• Light headedness and other sedative effects can happen
• Advised to avoid driving and monitor for addiction

Guaifenesin + Action/Indications/Side Effects

• Dextromethorphan (DM/DXM) that has antitussive qualities with sedative characteristics as well
• Indication for dry cough as a suppressant to cough
• Side effects can also be drowsiness and constipation with need to avoid driving after use

Antitussives Nursing considerations

• Do not drive or operate machinery
• Avoid depressants like alcohol
• Increase fluid intake and stay in cool atmosphere
• Stand and swap positions slowly
• Understand what you are taking this drug and education side of it
• Reduce prolonged the drug use and dependency of addiction
• Monitor cough for a week and report any changes needed
• Report any serious tract or lung issues

Expectorants – Function and Considerations

• Action of expectorants is to reduce fluid or mucous in needed areas, ex: lungs
• Action – productive cough with the help of increased fluid intake
• Side effects include vomiting and gastrointestinal issues
• Examples - Guaifenesin and Ammonium/Ipecacuanha blend(MES)

Mucolytics – traits and attributes.

• Traits - Mucolytic which helps break up mucous secretions
• Usage - Used to breakup and liquefy mucus from plugs and secretion
• Side reaction – vomiting rash and inflammation related to mouth and lips
• Types - Ambroxol and Bromhexine.

Mucolytics - Acetylcysteine

• Mucolytic, it contains N-acetylcysteine that facilitates clearity from mucus proteins
• It works the granuoles in a oral solution at 200 mg around 2/3 times daily.
• In a effervescent type of day with tabs of 600mg
• Drink more water is recommended

Teaching Respiratory Patients - Points

• Teach patients with proper inhalation when medicine is needed that use puffs, nebulizer and many more devices
• Prevent bronchospasm/irritants from smoking
• Use bronchodilator before usage

Patients using Respiratory medicine

1. Monitor therapeutic effects of drugs
2. Monitor side effects of drugs
3. Observe tremors or changes
4. Rinse mouth after inhilation to maintain oral hygiene and infection

Overview of respiratory medications, including bronchodilators and anti-inflammatory agents. Discussion of how drugs affect the autonomic nervous system, influencing airway dilation and constriction through sympathetic and parasympathetic pathways. Examples include adrenergic drugs, anticholinergics and cholinergic drugs.