Transcript Common Cold
Common Cold Common Cold • It is a self-limiting viral infection of the upper respiratory tract • Accounts for ½ of all ilnesses in adults and ¾ of all illnesses in infants • causes more time off work/school than any other illness • Common cold cannot be prevented or cured • Antibiotics: ineffective Common Cold • “coryza”, “acute infectious rhinitis”, “catarrh”. • The main and common causative agents: 5 viruses - rhinoviruses 50% of cases - coronaviruses, respiratory syncytial virus (RSV), influenza virus (types A,B,C); echovirus; coxackie virus, adenovirus, parainfluenza virus How does it transmit? Modes of Transmission • Inhalation of the virus in sneezed aerosols or droplets • Ingestion of saliva by eating or drinking implements • Hand-to-hand contact with infected person followed by rubbing the eye or nose Predisposing Factors • The factors that increase the susceptibility to viral URT infections are: 1. Smoking, 2. Sedentary lifestyle 3. Chronic psychological stress (e.g. ≥ 1 month) 4. Increased population density 5. Allergic disorders of the URT 6. Less diverse social networks Pathophysiology 1. Rhinoviruses bind to intercellular adhesion molecule on epithelial cells in the nose and nasopharynx 2. The virus replicates and infection spreads 3. Infected cells release chemokine “distress signal” and cytokines that activate inflammatory mediators & neurogenic reflexes results in Pathophysiology • a series of biochemical & immunological events that result in the release of inflammatory mediators vascular permeability glandular secretion Sneeze & cough reflexes Nasal Secretion Parasympathetic stimulus Stimulation of pain nerve fibers Signs & Symptoms Symptoms appear in sequence 1-3 days after infection: • The 1st symptom to appear: sore throat • 2nd : nasal symptoms (stuffiness (congestion), rhinorrhea, postnasal drip) • Watering eyes, sneezing • Then, cough (infrequent) by day 4-5 Less common: headache, chills, pyrexia (<37.8), sinus pain & myalgia 10 Complications • Virus-induced inflammatory changes in the nose may spread to other nearby structures (e.g. Sinuses, Eustachian tube) • This may lead to sinusitis, Eustachian tube obstruction, otitis media & secondary bacterial infection • Complications in LRT: bronchitis, bacterial pneumonia, exacerbation of asthma & COPD Management of common cold • The effective means of prevention: frequent hand cleansing with soap or soap substitutes • Cold symptoms are usually self-limiting and resolve within 1-2 weeks whether treated or not • General therapeutic measures: rest & maintain fluid intake • Treatment with drugs usually is symptomatic and should be symptom specific. Homework • Nonpharmacological therapies (p. 179) • Increase fluid intake. • Humidifiers and Vaporizers. • Intranasal saline sprays/drops/washes. • Breathe Right nasal strips. • Lozenges and demulcents. • Warm salt gargles. 18 Self-care for common cold Symptomatic OTC drugs for common cold Symptom Treatment Nasal congestion & discharge Cough Decongestants Sore throat Laryngitis Feverishness and headache Hydration, demulcents, antitussive, expectorants/steam vapors Demulcents, saline gargles, local anesthetics, systemic analgesics Cool mist/steam vapors Systemic analgesics ACCP Practice Guidelines 2006 21 Decongestants • Mainstay treatment of common cold • Vasoconstrictive drugs that decrease nasal congestion • Examples, systemic: phenylephrine, pseudoephedrine, ephedrine topical: naphazoline, tetrahydrozoline Antihistamines • Combination of first generation agents with decongestants showed some benefit in common cold symptoms relief • But benefit may not outweigh the risk Analgesics & Antipyretics • Common cold is rarely associated with temperature > 37.8°C • Patient complains of feeling feverish • Aspirin & paracetamol are effective • Aspirin: Never in children < 16 years old ??? Expectorants & Mucolytics • Expectorants: oral agents that aid in removal of respiratory tract secretions by either increasing bronchial secretions or facilitating their expulsion • FDA has classified Guiafenesin the only monograph expectorant (all others; terpin hydrate, ammonium chloride, iodides etc) nonmonograph • It is not effective in common cold • Mucolytics: thin mucus, making it easier to expel secretions e.g. Ambroxol, Carbinoxamine, Erabestein, Bromhexin (not OTC in US & UK) Expectorants & Mucolytics • Guiafenesin acts as expectorant by reflex gastric stimulation, thus, it doesn’t thin the sputum or increase production even at high doses • GIT side effects rarely at recommended doses • Camphor, eucalyptus oil, peppermint oil, Na citrate, pine tar, tolu balsam, turpine oil added to cold products for their “claimed” but unproven expectorant properties Antitussives • Inhibit/suppress cough • Indicated for suppression of dry, hacking & non-productive cough • Direct-acting antitussives (codeine, dextromethorphan & diphenydramine): 1. Suppress medullary cough centers of brain 2. Sensitivity of respiratory system cough receptors 3. Interrupt transmission of cough impulses Antitussives • Research has shown that antitussive in common cold are not more effective than placebo – not recommended • Antitussives should not be used in productive cough UNLESS it interferes with sleeping or is extremely bothersome, because it may impair the expectoration of secretions • Thus, combination products of cough suppressant and expectorants are irrational e.g. (in Jordan, Broncholar= DXM & guianfenesin) OTC in some countries Not in Jordan! Codeine • Is the standard antitussive, against which all other antitussives are compared • Dose in cough suppression (10-20 mg) is less than analgesic dose (30-60 mg) • Under the usual conditions of use as cough suppressant has lower dependency potential, however, dependence develop after prolonged use • Most common S.E: constipation, N&V, respiratory depression in sensitive patients or in large doses • Allergic reaction & pruritis less common Dextromethorphan • Dextrorotatory isomer of morphinan molecule • Has no analgesic properties, doesn’t depress respiration and has low addiction potential • May cause dependence • In higher doses of the abuse range intoxication with bizzare behaviour • Most common S.E: drowsiness & GIT upset • Never with MAOIs unless directed by a doctor Diphenhydramine • Antitussive & antihistamine • Acts centrally by suppression of medullary cough centre • S.E: sedation & anticholinergic effects • C/I: in narrow-angle glaucoma, benign prostatic hypertrophy • Additive effect: anxiolytics, sedatives, hypnotics or alcohol Topical Antitussives • The only monograph topical antitussives are camphor & menthol • They provide local anesthetic action by aromatic vapor when ointments rubbed on throat or chest as thick layer (maybe covered or not) • Both can be used as steam inhalation • Menthol also in lozenges & compressed tablets • Dangerous if accidentally ingested seizures • Clinical efficacy of camphor & menthol is not documented Anesthetics & Antiseptics • Lozenges, gargles, sprays containing antiseptics and local anesthetics (benzocaine, dyclonine HCl) promoted for treatment of sore throat • Antiseptics (e.g. hexylresorcinol, benzalkonuim chloride, amylmetacresol) ineffective for viral sore throat • Lozenges/hard candy: stimulates salivary secretion soothing demulcent • Warm saline gargles (1-3 tsp salt in 240-360ml warm water) or fruit juice may be effective Homework: • Decongestants compatible with pregnancy & lactation • Use of nonprescription cold medications in children < 2 years Common cold medications DO NOT have proven efficacies in children Am Fam Physician 2007;75:515-20, 522. 41 Controversies: vitamin C 43 Controversies: Zinc Zinc Common cold medications DO NOT have proven efficacies in children Am Fam Physician 2007;75:515-20, 522. 48 The last slide! • For common cold in children, do not rush into drugs • Safe remedies: tea & honey, chicken soup & hot broth. • Supportive measures: cleaning nose with bulb syringe, positioning the infant so that secretions can drain from nose, maintain adequate fluid intake • Using saline nasal drops or steam inhalation