Respiratory Drugs

Ventilation is the movement of air from the atmosphere through the upper and lower airways to the alveoli. Respiration is the process whereby gas exchange occurs at the alveolar-capillary membrane. Respiration has three phases:

• Ventilation is the phase in which oxygen passes through the airways. ⇒ Air
• Perfusion involves blood flow at the alveolar-capillary bed. ⇒ Blood
• Diffusion, the movement of molecules from higher to lower concentrations ⇒Air goes to the blood. Or Air goes from blood to the outside.

The common cold is caused by the rhinovirus and affects primarily the nasopharyngeal tract. Symptoms of the common cold include rhinorrhea (watery nasal discharge), nasal congestion, cough, and increased mucosal secretions. If a bacterial infection secondary to the cold occurs, infectious rhinitis may result, and nasal discharge becomes tenacious, mucoid, and yellow or yellow green.

The sympathetic and parasympathetic nervous systems affect the bronchial smooth muscle in opposite ways. The vagus nerve (parasympathetic nervous system) releases acetylcholine, which causes bronchoconstriction. The sympathetic nervous system releases epinephrine, which stimulates the beta2 receptor in the bronchial smooth muscle, resulting in bronchodilation. These two nervous systems counterbalance each other to maintain homeostasis.

Asthma is a condition where the airways get inflamed and narrow. It can be triggered by things like stress, allergens, or pollution. When triggered, the airways swell and tighten, making it harder for air to move through the lungs. The inflammation also makes the airways extra sensitive and causes extra mucus to form, which blocks airflow even more.

This leads to common symptoms such as wheezing, coughing, shortness of breath, chest tightness, and bronchospasms, especially at night or early in the morning.

Bronchial asthma is a COPD condition with episodes of bronchospasm, causing wheezing, mucus, and shortness of breath due to blocked airflow.

Bronchospasms are triggered by things like humidity, temperature changes, smoke, fumes, stress, emotions, exercise, and allergies (pets, dust mites, foods, and certain drugs like aspirin, ibuprofen, or beta-blockers).

Reactive airway disease is asthma caused by sensitivity to allergens, dust, temperature changes, or smoking.

In asthma, the lungs look normal when symptoms are not active. But in chronic bronchitis, emphysema, and bronchiectasis, lung damage is permanent. These conditions resemble asthma but usually do not cause wheezing and worsen gradually over time.

Eosinophil counts are usually elevated during an allergic reaction, which indicates that an inflammatory process is occurring. These chemical mediators stimulate bronchial constriction, mucus secretions, inflammation, and pulmonary congestion. Histamine and ECF-A are strong bronchoconstrictors. Bronchial smooth muscles are wrapped spirally around the bronchioles and contract as they are stimulated by these mediators. Exposure to an allergen results in bronchial hyperresponsiveness, epithelial shedding of the bronchial wall, mucous gland hyperplasia and hypersecretion, leakage of plasma that leads to swelling, and bronchoconstriction.

Key Mediators

• Histamine: Released from mast cells → causes vasodilation, bronchoconstriction, pain, and itching.
• H1 Receptors: Smooth muscle of vascular system & bronchial tree → itching, pain, edema, bronchoconstriction.
• H2 Receptors: In stomach → responsible for acid secretion.
• Prostaglandins: Formed by the enzyme Cyclooxygenase (COX).

⚖️ COX-1 vs. COX-2 Enzymes

💊 Two Primary Drug Classes Used for Inflammation

• NSAIDs: For mild to moderate pain, inflammation, and fever.
• Corticosteroids: For severe or disabling inflammation.

Drug: Diphenhydramine (Benadryl), Meclizine, Dimenhydrinate (-zine) – 1st generation

Fexofenadine (Allegra), Loratadine (Claritin), Cetirizine (Zyrtec) – 2nd generation (less drowsy) !!When in doubt 2nd generation is better.!!

Action: Competes with histamine for H1 receptor sites → prevents histamine response.

Use: Allergic rhinitis, cold symptoms, allergic reactions, motion sickness.

Contraindications: Severe liver disease, narrow-angle glaucoma, BPH, urinary retention.

💡 Notes:

• 1st gen = crosses blood brain barrier (BBB) → drowsy ⇒ ! alert pt. not to drive or operate dangerous machinery when taking such medications.
• Don’t take this drug with anything that makes you drowsy, like alcohol, narcotics, hypnotics, or barbiturates.
• Take at night to reduce sedation.
• Use with caution in asthma.
• 2nd gen = does not cross BBB → less drowsy, longer duration (often once daily dosing), fewer anticholinergic effects, better tolerated in elderly.
• Cetirizine ⇒ Safer choice for pt with asthma.
• Avoid alcohol or other sedatives.
• Take at night to reduce sedation.

Use: Relieve nasal stuffiness.

Adverse Effect: Rebound congestion if used >3–5 days.

Caution: Hypertension or heart disease → may raise BP.

Drugs: Fluticasone (Flonase), Budesonide (Rhinocort)

Action: Local anti-inflammatory nasal sprays used to treat allergic rhinitis, nasal polyps, and chronic sinus inflammation by reducing local inflammation, swelling, and mucus in the nasal passages.

Use: Drug of choice for allergic rhinitis.

💡 Notes:

• Any drug or procedure that dry the nose or reduces the nose secretions has the risk for nasal irritation ⇒ epistaxis

Action: Dampen/ suppress cough reflex in CNS used for dry, non-productive coughs to help patients rest or prevent irritation.

Caution: Use carefully in asthma or COPD patients. (this pts. have secretions)

1. Shake inhaler.
2. Exhale completely.
3. Start inhaling slowly while pressing inhaler once.
4. Continue deep inhalation.
5. Hold breath for 10 seconds.
6. Wait 1–2 minutes between puffs.
7. If using bronchodilator + corticosteroid:
• Use bronchodilator first, wait 5 min, then corticosteroid.
• 1. Albuterol (wait 5 min) ⇒ 2. Ipratropium (wait 5 min) ⇒ 3.Steroids.
8. Rinse mouth after corticosteroid use → prevents thrush (fungus).

Medications that relax bronchial smooth muscle, leading to airway dilation → used in asthma, COPD, and other respiratory conditions to improve breathing.

• Mental health risks: Montelukast carries an FDA warning for possible serious neuropsychiatric side effects, including depression, anxiety, vivid dreams, agitation, and suicidal thoughts. These can occur during treatment or even after stopping.
• Mental health monitoring is essential—patients and families should watch for mood or behavior changes and report them immediately.

💉 Monoclonal Antibodies (Biologics) (-umab)

🧑‍⚕️ Nursing Considerations:

• Administered SC or IV in clinical setting.
• Monitor for anaphylaxis (observe 2 hrs after 1st dose).
• Expensive and for refractory cases only.

• Direct patients not to drive during initial use of a cold remedy containing an antihistamine because drowsiness is common.
• Tell patients to maintain adequate fluid intake. Fluids liquefy bronchial secretions to ease elimination with coughing.
• Teach patients not to take a cold remedy before or at bedtime. Insomnia may occur if it contains a decongestant.
• Encourage patients to get adequate rest.
• Inform patients that common cold and flu viruses are transmitted frequently by hand-to-hand contact or by touching a contaminated surface. Cold viruses can live on the skin for several hours and on hard surfaces for several days.
• Advise patients to avoid environmental pollutants, fumes, smoking, and dust to lessen irritating cough.
• Teach patients to perform three effective coughs before bedtime to promote uninterrupted sleep.
• Direct patients and parents to store drugs out of reach of children; request childproof caps.
• Advise patients to contact a health care provider if cough persists for more than 1 week or is accompanied by chest pain, fever, or headache.
• Encourage patients to cough effectively, to take deep breaths before coughing, and to be in an upright position.
• Inform patients that antibiotics are not helpful in treating common cold viruses. However, they may be prescribed if a secondary infection occurs.
• Encourage older patients with heart disease, asthma, emphysema, diabetes mellitus, or hypertension to contact a health care provider concerning the selection of drug, including OTC drugs.
• Antibiotics may be prescribed to prevent serious complications from bacterial infections.