W14 Cold Flu And Allergies Flashcards
Cold, flu objectives:
don’t need to memorise brand names unless in red font
● recognize key limitations and precautions of agents used to treat cold, flu, and/or allergies
● recommend supportive care treatment of cold, flu, and/or allergies considering patient-specific factors
Common cold stats — just familiarise
Most common virus responsible?
Symptoms last?
● typically acute, self-limiting
● viral, mostly rhinovirus (not the flu /influenza), with no known definitive cure (yet)
● symptoms typically last 7-10 days, but can persist for longer (ie, lingering cough)
● incidence declines with increasing age
● a leading cause of missed work and school
● cough alone results in up to 30 million primary care visits per year
● national spending on OTC cough and cold medicine industry was >$8 billion a year in 2018, higher now
Rhinitis: what is it?
Symptoms
Causes
Tx for both allergic and non-allergic?
Tx for allergic ONLY
= inflammation of the nasal mucosa
symptoms
● irritability
● hypersecretion
● obstruction
● post-nasal drip can manifest as throat irritation, cough
causes
● allergic (seasonal or perennial)
● infectious (viral, bacterial)
● non-allergic and non-infectious
for both allergic and nonallergic rhinitis
DADS
● avoiding irritants
● ⭐️ saline irrigation
● ⭐️ topical or oral sympathomimetics (x2 decongestants)
● ⭐️ topical anticholinergic
* patients should be instructed to use bottled distilled water, and/or boil tap water for at least 1-3 minutes in advance (and then cooled to room temp*
typically only for allergic rhinitis (limited utility if nonallergic)
CALM
● ⭐️ topical Corticosteroids
● ⭐️ oral and topical Antihistamines
● ⭐️ Mast cell stabilizers
● ⭐️ Leukotriene inhibitors
● immunotherapy
consider topical agents if symptoms are limited to the nasal passage, oral agents if more widespread; consider combining multiple agents with differing mechanisms of action
sympathomimetics / decongestants
MOA:
ɑ agonism → vasoconstriction of arterioles in nasal mucosa → decreased swelling, fluid production
used for temporary relief of
● nasal/ear congestion
● rhinitis, post-nasal drip (often presents as throat pain, irritation)
adverse effects (oral > nasal)
● cardiac: hypertension, tachycardia, palpitations
● CNS: insomnia, restlessness, anxiety
precautions
● cardiovascular disease
● pregnancy (anything that vasoconstricts and compromises uterine bloodflow)
● topical agents - rhinitis medicamentosa; some systemic
exposure concerns - nasal or ophthalmic meds can absorb into the bloodstream in small amounts
TOPICAL (nasal) sympathomimetics / decongestants 2
Precaution, what is Afrin addiction?
Counselling point?
phenylephrine and oxymetazoline (longer-acting)
precaution:
—⭐️rhinitis medicamentosa: aka rebound
congestion, ‘Afrin Addiction’
● prolonged use leading to tachyphylaxis and
severe rebound congestion when discontinued
● treatment options: discontinuation, ?intranasal corticosteroids and other agents listed in the following slides w/ different MOA’s
key counseling point:
—use for no more than 3 days (this is stated on the packaging)
available OTC
ORAL sympathomimetics / decongestants — 2
pseudoephedrine
● often found in combination with antihistamines, as indicated by the “D” (for decongestant) in Zyrtec-D or Claritin-D
● ⛔️sold ‘behind the counter’ or in a secure location, max amount allowed per purchase and per individual per month (ID required)
phenylephrine (PE)
● in over 200 combination cold and flu medications (not sold on its own)
● not really effective!
available OTC
multiple studies, including some funded by the pharmaceutical companies that make cold/flu products with phenylephrine, show that it is no better than placebo. FDA is currently reviewing whether to keep it on the market
topical (intranasal) anticholinergics
(Anti-muscarinic)
ipratropium bromide 0.03% or 0.06% Rx only
MOA:
—inhibits serous and seromucous gland secretions
labeled indications
● allergic/nonallergic perennial rhinitis
● seasonal allergic rhinitis
● rhinorrhea due to colds
for allergic rhinitis, less effective compared to
intranasal corticosteroids, so not typically first-line
Allergic rhinitis
Pathophysiology
prevalence:
—affects up to 25% of the population, incidence increases in adolescence and peaks in the 30s-40s
pathophysiology
● IgE mediated (type I) reaction to an allergen
● late-phase or cellular reaction: release of cytokines and leukotrienes → chemotaxis of inflammatory cell (eosinophils), starts hours after initial sensitization and may last for up to 48 hours
● seasonal and/or perennial
Allergic rhinitis
Allergens
s/s
allergens:
—typically environmental (pollen, mold spores, dander, tobacco smoke, car exhaust), foods, insect stings
s/sxs:
—clear rhinorrhea
—congestion, sneezing,
—itching, postnasal drip
not life-threatening, but can severely impact quality of life - functionality, energy levels, sleep quality, etc.
children - learning difficulty
topical (nasal) corticosteroids
MOA
Which options, know the top 3
ADRs
Precautions
MOA:
↓inflammatory mediators and cytokines, ↓lymphocyte proliferation
highly effective for allergic rhinitis, possible utility for nonallergic rhinitis and polyps, requires up to 1 week of use for full effect
multiple options, all are equally effective
● ⭐️ fluticasone (Flonase®) - OTC
● ⭐️ triamcinolone (Nasacort® AQ) - OTC
● ⭐️ budesonide (Rhinocort® AQUA) - OTC
● mometasone (Nasonex®)
● and various others
adverse effects
—are mostly local (burning, stinging, dryness, epistaxis)
precautions
● local injury or respiratory infection
● glaucoma, cataracts
Oral antihistamines
ΜΟΑ
Οreal: 1st gen and 2nd gen
Argument for 2nd gen anti-histamines
MOA:
—competes w/ histamine for H1 receptor sites on effector cells located in blood vessels and the respiratory tract
oral (many):
● 1st gen: ⭐️diphenhydramine (Benadryl®),
chlorpheniramine, and others
● 2nd gen: ⭐️ cetirizine (Zyrtec®) ⭐️,
levocetirizine (Xyzal®), ⭐️ loratadine
(Claritin®) ⭐️, desloratadine, fexofenadine (Allegra)
most are OTC
the argument for 2nd-gen antihistamines
● less lipophilicity = less adverse effects (anticholinergic effects, particularly sedation and next-morning ‘hangover’); we’ll review more anticholinergic SEs with inhaler meds
● longer duration of action, typically taken once-daily
● levocetirizine (R-enantiomer of cetirizine) - double the H1 receptor binding affinity so more potent, less sedating; Allegra is also generally considered to be less-sedating than Zyrtec and Claritin
topical (nasal and ophthalmic) antihistamines
MOA:
—competes w/ histamine for H1 receptor sites on effector cells, which are located in blood vessels and the respiratory and GI tract
topical/nasal:
● ⭐️azelastine (Astepro®) ⭐️ - nasal, ophthalmic
● olopatadine (Pataday®) - nasal, ophthalmic
● cetirizine
the two pictured are OTC, the rest are Rx-only
mast cell stabilizers —2
(these are also antihistamines - prevent histamine release, rather than blocking receptors)
MOA:
—inhibits histamine degranulation from mast cells
for preventive purposes - must be started prior to allergen exposure (ideally 1-2 weeks beforehand)
common examples:
● ⭐️ cromolyn (nasal spray, oral, oral inhalation, and ophthalmic drop)
● ⭐️ ketotifen (ophthalmic, oral)
cromolyn nasal spray and ketotifen eye drops are OTC
the rest are Rx-only
Nasal spray administration
Just FYI
● prime before first use, or if not used in awhile
● clear nasal passages in advance (blow or rinse)
● spray tip should be inserted no more than ½ inch
into the nose
● leaning forward slightly, and pressing close the
nostril not being treated; some sprays require
gentle nasal inhalation
● spray away from the septum (ie, towards the ear)
to minimize adverse effects (esp epistaxis) and
ensure medication reaches the back of the nose;
easiest to hold w/ contralateral hand
● wipe and clean spray tip and recap after each use
leukotriene receptor antagonist
MOA
Uses?
Which agent
MOA:
—inhibition of leukotriene, pro-inflammatory
chemicals that are particularly well-known in for their role
in the pathophysiology of asthma
⭐️montelukast (Singulair®) ⭐️ and zafirlukast (Accolate®) for…
● allergic rhinitis if refractory to other options, or if coexisting asthma
● maintenance therapy of asthma
● prevention of exercise-induced bronchoconstriction
● various allergy-related off-label uses
BBW posted in 2020: serious neuropsychiatric events
(agitation, aggression, depression, sleep disturbance,
suicidal thoughts)
Rx only
Cough (Tussis)
Which is the only med that has been shown to decrease cough count, effort and frequency ?
note: despite widespread use, most antitussives lack strong evidence showing that they work better
than placebo, and there is a known placebo effect; only dextromethorphan has been shown to decrease cough count, effort, and frequency
Guaifenesin
MOA
When is it indicated?
NOT indicated for?
Known brand names?
MOA:
expectorant - thins and loosens mucus, possible direct effects on respiratory epithelial cells and cough-reflex sensitivity
for short-term management of acute, ineffective, productive coughs only; NOT indicated for chronic cough d/t chronic
lower respiratory tract disease (COPD, smoker’s cough, asthma, etc.)
well-tolerated (few adverse effects)
OTC
available own its own (Mucinex®, Robitussin®) and in numerous combinations:
● w/ codeine
● w/ codeine and phenylephrine
● w/ dextromethorphan (DM)
● w/ hydrocodone
● and lots more
other antitussives (cough suppressants)
for short-term treatment of productive and non-productive coughs
OTC
Tx
OTC topical agents
OTC
● dextromethorphan
● diphenhydramine
Rx only
● benzonatate
● promethazine
● codeine and other opioid derivatives
OTC topical agents
● menthol - activates nasal sensory afferents, in various cough and throat products
● benzocaine (Cepacol®, Chloraseptic®) - local anesthetic
● camphor (ie, Vicks®) - vapors help w/ cough and congestion
dextromethorphan
MOA
ADR
Precautions
MOA:
—analogue of levorphanol (a codeine analog), acts
centrally on the medulla, increases cough threshold
adverse effects
● GI: nausea/vomiting, discomfort
● CNS: drowsiness, dizziness
precautions
● caution w/ other sedating drugs and alcohol
● must be >18yr to purchase d/t abuse (‘robotripping,’
‘skittling,’ etc.)
● overdose → euphoria, visual hallucinations, etc.,
effects are similar to PCP and ketamine
● serotonin reuptake inhibition = risk of serotonin
syndrome with other drugs of similar effect (ie,
antidepressants), contraindicated with MAO
inhibitors
available on its own (Delsym®) as well as in numerous combination products…
● guaifenesin-dextromethorphan (Robitussin DM, Mucinex DM)
● promethazine-dextromethorphan
● and tons more
topical agents - benzocaine, menthol, camphor, etc.
Adverse affects to know
Benzocaine: methemoglobinemia
Camphor: if ingested, can cause severe CNS toxicity (incl. agitation, seizure, respiratory depression, coma)
benzonatate (Tessalon®)
MOA
Age in kids
Route
ADRs
MOA:
—precursor to tetracaine, which has local anesthetic (numbing) effects on respiratory stretch receptors
for use in adults and children >10yo
gel caps must be swallowed whole (if chewed, contents can cause local numbness and choking hazard)
adverse effects are uncommon, but may
include:
● constipation
● dizziness
● fatigue
● stuffy nose
● nausea
● headache
overdose → local anesthetic toxicity incl seizures, coma, cardiac arrest (more to be covered in surgery module); recent increasing trends of this happening in children because the gel caps look like candy
Promethazine
MOA:
—anticholinergic/antihistamine
→bronchodilates, reduces edema and congestion
note: first-generation antihistamines (ie, diphenhydramine) also work for cough because they penetrate the blood brain barrier and exert antihistaminic and antimuscarinic effects
on the medulla; second-gen antihistamines (ie, loratadine, cetirizine) do not have antitussive effects
adverse effects are the same as you’d expect
from other anticholinergics, esp drowsiness, dizziness
on its own (Phenergan®), promethazine is mainly used to treat nausea and vomiting
for cough and congestion, typically given in combination…
● w/ codeine
● w/ dextromethorphan
● w/ phenylephrine
● w/ phenylephrine and codeine
● etc
Codeine
MOA
In combo with?
ADRs?
Precautions! Contraindicated in?
MOA:
—metabolized to morphine, acts centrally on the medulla, increases cough threshold
always in combination form, such as…
● promethazine-codeine
● guaifenesin-codeine (Robitussin AC®)
● hydrocodone-chlorpheniramine (Tussionex®)
(there’s also acetaminophen-codeine for pain)
adverse effects:
● nausea/vomiting
● sedation
● dizziness
● constipation
precautions
● contraindicated in children <12 yo
● elderly
● impaired respiratory function
● substance abuse - mixed w/ soda +/- candy to make ‘purple drank,’ ‘lean,’ ‘sizzurp,’ ‘syrup,’ etc.
oral analgesics and antipyretics (anti-fever)
● aspirin - caution hypersensitivity and GI ulcers
● NSAIDs - caution hypersensitivity and GI ulcers, cardiovascular disease, pregnancy
○ one study found that patients who used NSAIDs during an acute respiratory infection tripled their risk of an acute myocardial infarction
● acetaminophen - caution exposure from multiple sources, liver injury if
overdose
precautions in special populations
Which cold and flu meds to avoid for:
Pregnancy, HTN, CVD (3)
Children <2y.o
herbals and supplements worth mentioning
combo cold and flu products - don’t get them mixed up!
● Robitussin Maximum Strength
Cough and Chest Congestion DM =
guaifenesin + dextromethorphan
● Robitussin Maximum Strength
Nighttime Cough DM =
dextromethorphan + doxylamine
● Robitussin Children’s 12 Hour
Cough Relief Medicine =
dextromethorphan
● Robitussin Children’s Nighttime
Cough Medicine =
chlorpheniramine +
dextromethorphan
caution prescribing or recommending agents by brand name
if a patient shares that they tried a brand name agent, dig further to determine what active ingredients it contains so that your recommendation is well-informed
look out for potential overdose due to overlapping ingredients from multiple sources
⭐️Know this BBWs for promethazine and codeine
Metabolised to morphine and causes respiratory distress
Absolute no-no in under 12
And post surgery
