Pneumonia is an acute respiratory infection of the lung parenchyma caused by one or co-infecting pathogens. These pathogens cause the lung parenchyma (alveoli) to become inflamed and fill with pus and fluid, limiting oxygen intake and making gas exchange ineffective.
In these notes, we’ll be going over the Pneumonia Pharmacology as well as the medical tests required to determine the severity. But before getting into that, make sure that you’ve understood the:
Introduction to Pneumonia Pharmacology
When treating Pneumonia, the main goal is to support the respiratory system and improve gas exchange. The most efficient way to do this would be to directly target the infecting pathogen, but it’s not always possible. As we mentioned in previous notes, Pneumonia can be caused by several different pathogens, all of which can be viral or bacterial. If the patient tests positive for a bacterial pathogen, then antibiotics will be prescribed to stop the infection.
However, if the pathogen is a virus, antibiotics won’t work and no medication would stop the infection. The patient’s body would have to fight it off naturally, and all we can do is treat the symptoms. In addition, there are several cases where the infecting pathogen is not discovered because the sputum samples or blood cultures would not be conclusive. So again the pharmacological treatment would be supportive.
Pneumonia Pharmacology: Antibiotics
When a patient is diagnosed with bacterial Pneumonia they are typically started on broad-spectrum IV Antibiotics to suppress the infection as early as possible. The choice of antibiotics depends largely on the patient’s condition and whether they have any known Multi-Drug Resistance (MDR).
Patients who have no known MDR are typically prescribed monotherapy, meaning only one antibiotic. With the most common choices being:
On the other hand, patients with a known MDR are treated much more aggressively, and they will often be prescribed a three-drug combination therapy. Typically, the patients would get two Anti-Pseudomonal Antibiotics such as:
And another antibiotic including:
Table 1 Give an Overview of Antibiotics used in Pneumonia
*This information does not contain all possible side effects and drug interactions, it is for educational purposes only.*
Cephalosporins 1st Generation
Cephalosporins 3rd Generation
Tazobactam - Piperacillin
No known severe drug interactions
Abnormal liver function tests
Flushing of face
Low blood pressure
Pneumonia Pharmacology: Oxygen Therapy
Pneumonia affects the individual’s respirations which often results in limited oxygen uptake and hence a decrease in oxygen saturation within the body. Oxygen therapy aims to keep the patient’s arterial oxygen saturation (SpO2) above 92% and their partial pressure of oxygen in the blood over 60 mmHg. However, lower values might be accepted if the patient has any chronic respiratory illnesses such as COPD as they would be at risk of developing carbon dioxide retention.
The mode of administration for oxygen therapy depends on the patient’s physiological condition and the amount of oxygen they need to keep their SpO2 within a normal range:
Nasal cannula delivers up to 5L/min
Normal face mask delivers up to 15L/min
A non-Rebreather mask can be used to administer a high-flow system
Moreover, if hypercapnia occurs, the patient might need Non-invasive positive pressure ventilation (NPPV) which pushes oxygen into the patient’s lungs and forces carbon dioxide out of the lungs.
Pneumonia Pharmacology: Mucolytics
When a respiratory infection occurs, the airways become irritated and start to produce excessive amounts of mucus to act as a physical barrier against irritants. However, apart from blocking the irritants, the mucus will also limit oxygen intake and obstruct airflow. The only way to clear out the excess sputum is to cough it up but in some cases, this might be challenging. Either because the mucus would be very thick or because the patient would be frail and wouldn’t have enough energy to cough effectively.
In either of these cases, Mucolytics are prescribed to decrease the viscosity of the mucus and make it easier to expectorate it (cough it up).
The most commonly used Mucolytics are:
N Acetyl Cysteine
Pneumonia Pharmacology: Expectorants
Similar to mucolytics, the aim behind the use of expectorants is to help the patient clear their airways from the build-up of mucus. With most of the expectorants being derived from plants, their use is sometimes overlooked. However recent studies have shown that botanical expectorants reduce the viscosity of mucus and assist patients to cough up secretions more easily. Moreover, some of these medications also have antibacterial, antiviral and antitussive properties, giving them an overall advantage to their use in respiratory illnesses.
The most commonly used expectorants are:
Pneumonia Pharmacology: Antipyretics
Like any other infection, pneumonia will likely cause a spike in fever so antipyretic medication is prescribed to suppress the high temperature. While NSAIDs such as ibuprofen or aspirin are great at treating fever, they are contraindicated in respiratory illnesses as they might worsen the patient’s condition. Several studies show that NSAIDs negatively affect the local airway immunity and they’ve also been linked to higher complications during active pneumonia.
With this in mind, Paracetamol becomes the first choice of antipyretic when treating pneumonia. In addition, Paracetamol also acts as an analgesic which becomes useful if the patient is experiencing a headache or muscle pains during the infection.
Those are the most commonly used drugs when caring for patients with pneumonia.
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