Update on Respiratory Tract Infections

Article excerpt

Upper respiratory tract infections (URTI or URI) are the most common acute illnesses in the general population. Symptoms often involve one or more sites of the respiratory system, including the sinuses, nasal passages, pharynx, and larynx. This results in a substantial number of visits to primary care providers, the emergency room, and ultimately the local pharmacy for either prescription medications or nonprescription symptomatic relief. Pharmacists should be familiar with the etiology and potential treatments for these infections. In doing so they may educate their patients on realistic expectations of antibiotic use, general prevention methods, and assist with referrals to a primary care provider when appropriate.

The common cold

The symptoms associated with the "common cold" are actually caused by at least five major groups of respiratory viruses, including the rhinoviruses and coronaviruses. The rhinovirus group, which is responsible for at least 50% of infections in adults, includes at least 100 types and one subtype. The genetic variation limits the ability for vaccine development as well as the body's ability to achieve immunity against the "common cold."

It is estimated that the economic impact of colds is $40 billion annually in the United States. These cold epidemics occur annually, often in the winter months in the United States. The rhinovirus infection rates also have their seasonal variations in outbreaks. The rhinovirus attack rates are greater in early fall and mid to late spring. The coronaviruses are more prominent in the winter. These trends are likely influenced by the school year and indoor crowding, which facilitates the transmission of viral respiratory secretions among individuals. Viral transmission occurs by hand and mucous membrane exposure and in some cases contaminated surfaces. Frequent hand washing and avoiding hand contact with either the nose or eyes assists in reducing transmission, but aerosol exposure may still occur with some viruses.

The average adult averages two to four episodes of "colds" yearly and children average six to eight episodes. However, adults with children also experience a greater rate due to secondary exposure. Individuals who smoke do not experience a greater number of infectious episodes, but those that occur are more severe. Most infected individuals experience the symptoms of sore throat first, then nasal discharge and congestion, sneezing, and cough, with slight elevations of temperature (<100°F) occurring more often in younger children. Most symptoms resolve within a week, but 25% of patients will experience symptoms for two weeks. Rarely do individuals go on to experience secondary bacterial infections of the sinuses or middle ear in which antibiotic therapy is required. Thus, treatment currently remains limited to symptomatic relief.

Effective therapeutic options for symptomatic relief of sore throat, congestion, and cough in adults include local anesthetics, throat lozenges, systemic or topical decongestants, such as pseudoephedrine and phenylephrine, respectively, and firstgeneration antihistamines, such as diphenhydramine. Recent guidelines from the American College of Chest Physicians (ACCP) state that using dextromethorphan and guaifenesin for coughing associated with colds is not effective and may increase morbidity and mortality in patients, especially in children less than 14 years of age. Codeine and homatropine (Hycodan) have also been used as cough suppressants in patients, but their effectiveness has been questioned in treating cough due to colds. Alternative therapies, such as Echinacea, zinc, humidified air, and fluid intake, have not been proven to reduce the severity of symptoms either. High-dose vitamin C (> 2 grams) in some studies has reduced the severity and duration of symptoms in some adults. Additionally, patients with comorbid conditions, particularly hypertension, should be counseled on potential adverse effects associated with pharmacological therapies, particularly oral decongestants. …