pulmonary pharmacology - university of hawaii€¦ · asthma attacks - causes a prolonged narrowing...
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Pulmonary Pharmacology
JACOBS Wednesday, Feb 03
3:00 – 4:50 PM
PHPP 516 (IT-II) Spring 2016
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PULMONARY FUNCTION
TV = Tidal Volume TLC = Total Lung Capacity VC = Vital Capacity IC = Inspiratory Capacity
IRV = Inspiratory Reserve Volume ERV = Expiratory Reserve Volume FRC = Functional Residual Capacity RV = Residual Volume
Spirometer TV TLC
IRV IC
RV
ERV
FRC
VC
Spirogram
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• Asthma • COPD (emphysema and chronic bronchitis)
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OBSTRUCTIVE PULMONARY DISEASES
FVC = Forced Vital Capacity. = Volume that can be forcibly exhaled after a full inspiration (not timed)
FEV1 = Forced Expiratory Volume 1. = Volume that can be forcibly exhaled after a full inspiration IN ONE SECOND
OBSTRUCTIVE DISEASE = Difficulty Exhaling Quickly
• LOW FEV1 • LOW FEV1/FVC
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• Pneumonitis • Fibrosis • ARDS • etc.
RESTRICTIVE PULMONARY DISEASES
RESITRICTIVE DISEASE = Difficulty Inhaling Fully • Low FVC • Near normal FEV1/FVC
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• Acute inflammation of bronchi caused by various triggers, associated with airway ‘remodeling’
Acute (reversible) changes: • Leukocyte (WBC) infiltration • Mucous production • Bronchoconstriction
Chronic changes: • Persistent leukocyte (WBC)
infiltration • Less airway epithelium • More SMC, fibroblasts, goblet cells • More extracellular matrix
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ASTHMA
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- Alveolar destruction
- Poor gas exchange
- Reduced compliance (loss of elastic recoil)
- MAJOR cause = SMOKING (also air pollution)
• Permanent enlargement of gas-exchanging airways • Destruction of alveolar walls (w/no obvious fibrosis)
normal
emphysema
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COPD: EMPHYSEMA
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• Chronic inflammation of bronchi leading to mucus formation and muscle constriction
- Persistent (chronic) and productive cough (with sputum)
- Bronchial inflammation
- More mucus production
- Increased airway muscle tone (bronchoconstriction)
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COPD: CHRONIC BRONCHITIS
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Prostaglandins (PGs)
• Released by mast cells, eosinophils and Th2 cells
• Derived from arachidonic acid (AA)
• Produced in two steps from AA:
1. Cyclooxygenase-1 or -2 (COX-1 or COX-2), makes PGH2 (biologically inactive)
2. Various Prostaglandin synthases, make the active prostaglandins:
PGD2, PGE2, PGF2 PGI2 and TXA2
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INFLAMMATORY MEDIATORS
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Prostaglandin D2 (PGD2)
• Major contributor to asthma • Binds to DP1 receptor
• Actions (PGD2):
- Chemoattractant: Recruits eosinophils and Th2 cells
- Bronchoconstriction (asthmatics are typically more sensitive to PGD2)
- Vasodilation and edema (swelling) in airways
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INFLAMMATORY MEDIATORS
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Leuktotrienes (LTs)
• Released by mast cells and eosinophils • Derived from arachidonic acid • Produced by 5-lipoxygenase (5-LO), then GST
• Leukocytes in the airways release a mixture of cysteineyl leukotrienes (LTC4 LTD4 and LTE4) known as SRS-A (slow reacting substance of anaphylaxis)
- Secreted during anaphylactic reactions and asthma attacks - Causes a prolonged narrowing of airways.
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INFLAMMATORY MEDIATORS
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Leuktotrienes (LTs) SRS-A
• Binds to CysLT1 and CysLT2 receptor in airways • Extremely potent
• Actions (SRS-A):
- Chemoattractant: Recruits eosinophils and mast cells
- Activates mast cells: (degranulation, histamine release)
- Causes bronchoconstriction and edema (results in airway swelling)
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INFLAMMATORY MEDIATORS
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Membrane Lipids Phospholipase A2 (cPLA2)
Arachidonic Acid (AA)
Prostaglandins (e.g. PGD2)
COX-1 or COX-2 + PG synthases
5-LO + GST
Cysteinyl Leukotrienes (SRS-A)
DP1 receptor • Bronchoconstriction • Swelling • Eosinophil infilitration • Th2 infiltration
CysLT1,2 receptors • Bronchoconstriction • Swelling • Eosinophil infiltration • Mast cell activation 12
INFLAMMATORY MEDIATORS
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Histamine
• Released by mast cells
• Binds to H1 receptor in pulmonary smooth muscle and in the vascular endothelium (blood vessel lining)
• Actions:
• Causes bronchoconstriction (and airway narrowing)
• Increases vascular permeability: - Causes mucosal edema
(increases airway swelling and narrowing) - Allows leukocyte infiltration into tissues
(enhances inflammatory response)
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INFLAMMATORY MEDIATORS
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ECF-A (eosinophilic chemotatic factor of anaphylaxis)
• Peptide released by mast cells in response to antigen-stimulated activation of IgE’s on mast cell surface
• Actions:
- Released in an allergen-stimulated asthma attack
- Chemoattractant: Recruits eosinophils, worsens inflammation and prolongs the asthma ‘attack’
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INFLAMMATORY MEDIATORS
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INFLAMMATORY MEDIATORS
Antigen (allergen)
B-cells
Plasma cells
IgE Mast cells
ECF-A
Antigen (allergen)
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Parasympathetic Sympathetic
ACh NE/EPI
Muscarinic M1 M2
M3 M4 M5
GPCR
Alpha 1
2
GPCR
Beta 1
2
3
GPCR
Nicotinic (α1)2β1δε (α1)2β1δγ (α3)2(β4)3
(α4)2(β2)3
(α3)2(β4)3
(α7)5
Ion Channels
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NEUROGENIC CONTROL OF AIRWAYS
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Parasympathetic (VAGUS)
ACh
M3
Sympathetic (T1-T5) NE
(Adrenals) EPI
EPI>>NE
2
• Bronchoconstriction • Increased mucous
• Bronchodilation • Decreased mucous
resistance
1
r4
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NEUROGENIC CONTROL OF AIRWAYS
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2
Gs AC
ATP
cAMP PKA
K+
EPI
B. LOWER INTRACELLULAR CALCIUM PKA INHIBITS PLC/IP3/Ca2+
PATHWAY
AC = Adenylate cyclase PKA = Protein kinase A
A. LOWER MEMBRANE POTENTIAL (HYPEROLARIZED) DUE TO K+ EFFLUX
= SMC RELAXATION 18
NEUROGENIC CONTROL OF AIRWAYS
BK Channel
2 = airway dilation
C. LESS SMC CONTRACTION PKA INHIBITS MYOSIN LIGHT CHAIN KINASE (MLCK)
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2
Gs AC
ATP
cAMP
EPI
AMP
PDE
PHOSPHODIESTERASE (PDE) in pulmonary airways = LESS cAMP/PKA activity
= SMC CONTRACTION
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NEUROGENIC CONTROL OF AIRWAYS
PDE = airway constriction
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M3
Gq
HIGHER INTRACELLULAR CALCIUM LEVELS
ACh
Ca++
IP3R
PLC
PIP2 DAG
Ca++ Ca++ Ca++
IP3
Ca++ Ca++ Ca++ Ca++ Ca2+
PLC = Phospholipase C
= SMC CONTRACTION
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NEUROGENIC CONTROL OF AIRWAYS
M3 = airway constriction
= MORE SECRETIONS
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SHORT-ACTING: Albuterol (Proventil®) Epinephrine (Primatene®) Ephedrine Isoproterenol (Isuprel®) Levabuterol (Xopenex®) Metaproterinol (Alupent®) Pirbuterol (Maxair®) Terbutaline (Brethaire®)
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BRONCHODILATORS: Drug Classes
LONG-ACTING: Arformoterol (Brovana®) Formoterol (Foradil®) Indacaterol (Arcapta®) Olodaterol (Striverdi Respimant®) Salmeterol (Serevent®)
ANTICHOLINERGICS Aclidinium Br (Tudorza™) Ipratropium Br (Atrovent®) Tiotropium Br (Spiriva®) Umeclidinium Br (Incruse Ellipta®)
METHYLXANTHINES Aminophylline (theophylline) Dyphylline (Dylix®, Lufyllin®) Theophylline
SYMPATHOMIMETICS
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2
Gs
BETA2 AGONIST
AC cAMP PKA
ATP
2 agonists act as “FUNCTIONAL ANTAGONISTS”
• Antagonize bronchoconstriction by promoting the opposite effect (bronchodilation)
• They do not block the causative agent, they inhibit its actions at the “functional” level
Bronchodilation Broncho- constriction
Neurogenic Allergenic Chemical
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BRONCHODILATORS: Sympathomimetics
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DIRECT Actions (on SMC)
• Increases cAMP levels (and activates PKA) • Opens K+ channels (hyperpolarize SMCs) • Causes inhibition of Ca2+ release • Causes inhibition of MLCK
INDIRECT Actions (that also have therapeutic effect)
• Block release of inflammatory mediators from mast cells
• Prevent microvascular leak/edema during inflammation
• Activate presynaptic 2 receptors (parasympathetic nerves) which opens K+ channels and prevents depolarization (i.e. less release of ACh in the airways)
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BRONCHODILATORS: Sympathomimetics
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SHORT-ACTING BETA AGONISTS (SABA)
Albuterol* Levalbuterol* Metaproterinol Pirbuterol Terbutaline
(Non-Selective) Epinephrine Ephedrine Isoproterinol
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BRONCHODILATORS: Sympathomimetics
*Animal studies suggested that S enantiomers of 2 agonists increased airway responsiveness (worsens symptoms over time)
Albuterol = R/S (L/D) racemic mixture Levalbuterol = R (L) albuterol
Clinical data are still not conclusive
“Chiral Switch”
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SABA
USES: Commonly used as inhalation therapy for on-demand relief of Acute asthma attacks and Exercise-Induced Bronchoconstriction (EIB)
ADMIN: INHALATION (fewer side effects) but also available as ORAL (sustained release) and IV PK: Resistant to metabolizism by either catecholamine-O-methyltransferase (COMT) or monoamine oxidase (MAO) Onset: immediate Duration: 3-4 hr (lower in severe asthma)
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BRONCHODILATORS: Sympathomimetics
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BRONCHODILATORS: Sympathomimetics
LONG-ACTING BETA AGONISTS (LABA)
Arformoterol* (Brovana®) Formoterol* (Foradil®) Salmeterol (Serevent®)
* “chiral switch” Formoterol = R/S racemic Arformoterol = R formoterol
ULTRA LONG-ACTING BETA AGONIST (ultra-LABA)
Indacaterol (Arcapta Neohaler®) Olodaterol (Striverdi Respimat®) Vilanterol
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USES: maintenance therapy of Asthma and COPD ADMIN: INHALATION
Example fixed combination w/corticosteroids: • fluticasone/salmeterol (Advair®) • budesonide/formoterol (Symbicort®) • mometasone/formoterol (Dulera®)
PK: Resistant to metabolizism by either catecholamine-O-methyltransferase (COMT) or monoamine oxidase (MAO) Onset: 3 min – 50 min (depends on drug) Duration: 12 hr
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BRONCHODILATORS: Sympathomimetics
LABA
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USES: maintenance therapy of COPD ADMIN: INHALATION
Example fixed combination w/corticosteroids: • fluticasone/vilanterol (Breo Ellipta®)
Example fixed combination w/anticholinergics: • umeclidinium/vilanterol (Anoro Ellipta®)
PK: Resistant to metabolizism by either catecholamine-O-methyltransferase (COMT) or monoamine oxidase (MAO) Onset: 5 min Duration: 24 hr
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BRONCHODILATORS: Sympathomimetics
ultra-LABA
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Adverse Effects More common/severe with ORAL or IV route
TACHYCARDIA, PALPITATIONS caused by:
a. Reflex cardiac stimulation secondary to peripheral vasodilation (drop in bp)
b. Direct stimulation of atrial 2 receptors c. Stimulation of myocardial 1 receptors
(at high drug doses)
These side effects tend to disappear with continued use of the drug reflecting the development of tolerance
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BRONCHODILATORS: Sympathomimetics
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Adverse Effects More common/severe with ORAL or IV route
MUSCLE TREMOR (most common side effect) caused by: Stimulation of 2 receptors in skeletal muscle More troublesome with elderly (COPD patients)
RESTLESSNESS
METABOLIC EFFECTS Increases in FFA, insulin, glucose, pyruvate, lactate Typically only after a large systemic doses.
QTc PROLONGATION (dose-related)
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BRONCHODILATORS: Sympathomimetics
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Adverse Effects More common/severe with ORAL or IV route
HYPOKALEMIA
Stimulation of K+ entry into skeletal muscle from blood.
May be insulin-mediated, because 2 receptors cause insulin secretion
If a severe acute asthma attack is treated with bolus 2 agonist, you can get hypokalemia and hypoxia together, which can be dangerous (severe cardiac arrhythmias)
BRONCHODILATORS: Sympathomimetics
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Adverse Effects More common/severe with ORAL or IV route
VENTILATION/PERFUSION (V/Q) MISMATCH
2 agonists cause pulmonary vasodilation, which results in shunting of blood to poorly ventilated areas (previously constricted before being given drug)
This causes a fall in arterial oxygen tension (paO2)
Effect is more noticeable with severe COPD and is treatable with inspired O2
BRONCHODILATORS: Sympathomimetics
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AC PKA cAMP
ATP
Bronchodilation
PDE
AMP
cAMP Methyl- xanthines
MECHANISM 1: Phosphodiesterase inhibition
• Inhibit breakdown of cAMP • More cAMP = more bronchodilation
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BRONCHODILATORS: Methylxanthines
AC = adenylate cyclase PKA = protein kinase A (cAMP-activated) PDE = phosphodiesterase
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MECHANISM 2: Adenosine receptor antagonism (significance unclear, probably less important)
AC
ATP
cAMP A1
Ado
Gi
Methylxanthines
• “De-repress” (i.e. activate) adenylate cyclase • More cAMP = more bronchodilation • Also inhibit A2B receptors on mast cells (i.e. block mast cell activation)
PKA
Bronchodilation
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BRONCHODILATORS: Methylxanthines
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INFLAMMATORY CELL TYPES
AIRWAY CELL TYPES
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BRONCHODILATORS: Methylxanthines
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USE: Overnight prophylaxis of Asthma and COPD
ADMIN: Oral (sustained release)
IV aminophylline was used for several years for treatment of acute asthma attacks, but has largely been replaced by 2 agonists
METHYLXANTHINES Aminophylline (Theophylline ethylenediamine) Dyphylline Theophylline
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BRONCHODILATORS: Methylxanthines
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INCREASE CLEARANCE • CYP1A2 induction
(rifampin, barbiturates, ethanol, cigarettes)
• High protein diet • Children
REDUCE CLEARANCE • CYP1A2 inhibition
(cimetidine, Cipro®, fluvoxamine, erythromycin, zileuton, zafirlukast)
• CHF, Liver disease • High carbohydrate diet • Elderly
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BRONCHODILATORS: Methylxanthines
PK: Absorption is rapid and complete, but rates of clearance can vary significantly
Metabolism: Hepatic, CYP1A2
Duration: 12 hr (slow release formulation)
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Adverse Effects NARROW Therapeutic Window! (e.g. 5-15 mg/L for theophylline)
HEADACHE, NAUSEA, VOMITING (common), caused by inhibition of PDE4 in CNS GI UPSET, DIARRHEA caused by inhibition of PDE4 DIURESIS caused by antagonism of Ado A1 receptor
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BRONCHODILATORS: Methylxanthines
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Adverse Effects NARROW Therapeutic Window!
ARRHYTHMIAS Caused by
• Inhibition of PDE3 • Antagonism of cardiac A1 receptors
HYPERSENSITIVITY (mainly to the ethylenediamine component in aminophylline – i.e. not the active drug)
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BRONCHODILATORS: Methylxanthines
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Roflumilast (Daliresp®) FDA approved March 2011
AMP
PDE cAMP Methylxanthines
AMP
PDE4 cAMP Roflumilast
More specific for airways = fewer side effects But some side effects remain: • Diarrhea, weight loss • Headache • CNS effects (anxiety, depression) 40
BRONCHODILATORS: PDE4 Inhibitor
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Bronchoconstriction Airway secretions
M-Antagonists • Inhibit bronchoconstriction • Reduce airway secretions
41
M3
Gq PLC
ACh
Ca++
IP3R Ca++ Ca++ Ca++
IP3
Ca++ Ca++ Ca++ Ca++ Ca2+
BRONCHODILATORS: Anticholinergics
Anticholinergics
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USE: Control of asthma (off-label) and COPD
ADMIN: INHALATION
ABSORPTION (lungs): POOR (has + charge)
ONSET: 30-60 min
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BRONCHODILATORS: Anticholinergics
ANTICHOLINERGICS
Umeclidinium Br Aclidinium Br Tiotropium Br
LONG-ACTING (24 hr)
Ipratropium Br
SHORT-ACTING (6-8 hr)
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ACh
M3
M2
M2 is an autoreceptor that inhibits further ACh release
Bronchoconstriction Airway secretions
Inhibition of M2 increases ACh release and enables BRONCHOCONSTRICTION
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BRONCHODILATORS: Anticholinergics
nerve ending
ACh ACh
ACh ACh
Inhibition of M3 causes BRONCHODILATION
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ACh
ACh M2
M3
Bronchoconstriction Airway secretions
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BRONCHODILATORS: Anticholinergics
ACh ACh
ACh
Iporatropium
Iporatropium
Ipratropium is NONSPECIFIC for M2 and M3 receptors. It blocks M3-mediated bronchoconstriction and airway secretions, but can also enable vagally-mediated Ach release (which can outcompete ipratropium blockade of M3 receptors)
This effect can INCREASE ACh release!
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Newer agents preferentially block M3 receptors AND they have longer durations of action. Receptor specificity is due to differences in OFF RATES. Although they are not selective in binding they dissociates VERY SLOWLY from M3, so inhibit M3>M2 (because they stay bound to that receptor for a long time)
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BRONCHODILATORS: Anticholinergics
OFF-RATES M3 < M2
(drug dissociation from M3 are 50-200x SLOWER than ipratropium!)
M3 M2
ON RATES M3 = M2
M3 M2
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BRONCHODILATORS: Anticholinergics
Ipratropium – partially metabolized by esterases (half-life: 2 hr)
Aclidinium – rapidly metabolized by esterases (half-life: 5-8 hr)
Tiotropium – not metabolized (half-life: 5-6 days)
Umeclidinium – metabolized by CYP2D6 (half-life: 11 hr)
Metabolism (and circulatory half-lives)
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Adverse Effects (Minor, generally well tolerated)
DRY MOUTH AND UPPER AIRWAYS (common) Systemic (PNS, not local) effect of drug – less incidence with aclidinium because of rapid metabolism
COUGH
UNPLEASANT TASTE
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BRONCHODILATORS: Anticholinergics
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Drug Interactions
BRONCHODILATORS: Anticholinergics
Tachycardia caused by cannabis
Constipation and urinary retention caused by opiates
Will enhance the side effects of other anticholinergics drugs.
Examples:
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Magnesium Sulfate (MgSO4)
Used IV or inhalation in combination with 2 agonist in clinical studies in emergency setting (acute asthma attack) when FEV1 <30% normal
Mechanism: Reduces intracellular Ca2+ in SMC Side effects: Flushing and nausea Onset: IV immediate Duration: 30 min
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BRONCHODILATORS: Other Agents
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Vasoactive Intestinal Peptide (VIP) Analogs
VIP binds to two GPCRs (VPAC1 and VPAC2) that couple to Gs and lead to SMC relaxation.
Ro 25-1533 is a stable VIP analog that selectively binds to the airway receptor (VPAC2) and causes SMC relaxation.
Effect is rapid, but not lasting
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BRONCHODILATORS: Other Agents
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IkB P
NF-kB
Inflammatory Genes
INHIBIT gene expression • Less cytokine production • Less of certain WBC types
Inflammatory Stimuli
IkB
Corticosteroids
GR NF-kB
WBC 51
INHALED CORTICOSTEROIDS
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Some of the genes INHIBITED by corticosteroids
Phospholipase A2 Less eicosanoids (prostaglandins and leukotrienes)
Cyclooxygenase-2 (COX-2) Less prostaglandins
Th2 Cytokines Less inflammatory signaling molecules (IL-4, IL-5, IL-9 and IL-13)
Extracellular proteases Less vascular leak and airway remodeling
Cell survival genes Causes fewer of some WBC types
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INHALED CORTICOSTEROIDS
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Anti-inflammatory actions of corticosteroids in the airways
IMMUNE CELLS AIRWAY CELLS
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INHALED CORTICOSTEROIDS
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Beclomethasone (QVAR®) Triamcinolone Flunisolide (Aerobid®)
Low systemic bioavailability drugs: Budesonide (Pulmicort®) Fluticasone hemihydrate (Aerospan®) Fluticasone propionate (Flovent®, Flonase®) Mometasone furoate (Asmanex®, Nasonex® - nasal spray) Ciclesonide (Alvesco®) i.e. Less side effects
if swallowed
DPI MDI DPI
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INHALED CORTICOSTEROIDS
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Ciclesonide is a prodrug that is converted to an active metabolite by esterases in the lung epithelium
USES: Asthma and COPD – Inhalation Exercise-induced bronchoconstriction (EIB) – Inhalation Allergic rhinitis (Hay fever) – Nasal spray
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INHALED CORTICOSTEROIDS
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Fate of inhaled corticosteroids (and other inhaled drugs)
MDI = metered dose inhaler (HFA-charged aerosol) DPI = dry powder inhaler
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INHALED CORTICOSTEROIDS
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LOCAL Adverse Effects (airways) Dysphonia (hoarse voice) Oropharyngeal candidiasis (thrush) Cough
SYSTEMIC Adverse Effects Adrenal suppression and insufficiency Easy bruising, thin skin Osteoporosis Cataracts (spray in eyes) Glaucoma (spray in eyes) Metabolic abnormalities (glucose, triglycerides) Psychiatric disturbances (euphoria, depression) Immune suppression (pneumonia) 57
INHALED CORTICOSTEROIDS
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5-LO INHIBITORS Zileuton (Zyflo®, Zyflo CR®)
CysLT1 RECEPTOR ANTAGONISTS Montelukast (Singulair®) Zafirlukast (Accolate®)
USES: Asthma (All agents) - ORAL Exercise-induced bronchoconstriction (EIB) (Montelukast) - ORAL Allergic rhinitis (Montelukast) - ORAL
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LEUKOTRIENE ANTAGONISTS
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LEUKOTRIENE ANTAGONISTS
5-LO inhibitors
LT antagonists
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Zileuton – PK Metabolism: Hepatic, several P450 isoforms Elimination: Renal (as metabolites) Half-life: 2.5 hr (short)
Immediate release: four times daily Extended release (ER): twice daily
Adverse Effects Sinusitis, URI (5-9%) Upset stomach, nausea (5-8%) Elevated ALT (2-5%)
Drug Interactions Theophylline – Zileuton may inhibit theophylline clearance
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LEUKOTRIENE ANTAGONISTS
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Montelukast – PK Absorption: Rapid (63-73% bioavailable) Metabolism: Hepatic, CYP2C9, CYP3A4 Elimination: Feces (as metabolites) Half-life: 2.7-5.5 hr (once daily) Adverse Effects (minor)
Increased serum AST (about 2%) Drug Interactions
CYP2C9 or CYP3A4 Inducers (rifampin, barbiturates) may montelukast levels CYP2C9 Strong Inhibitors (fluconazole) or CYP3A4 Strong Inhibitors (protease inhibitors, clarithromycin, telithromycin, chloramphenicol) may montelukast levels 61
LEUKOTRIENE ANTAGONISTS
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Zafirlukast – PK Absorption: REDUCED BY FOOD (40% Lower) Metabolism: Hepatic, CYP2C9 Elimination: Feces (as metabolites) Half-life: 20 hr (twice daily) Adverse Effects (minor)
Eosinophilic conditions (Churg–Strauss syndrome) “controversial”
Drug Interactions CYP2C9 Inducers (rifampin, barbiturates) may lower levels of zafirlukast CYP2C9 Strong Inhibitors (fluconazole) may raise levels of zafirlukast
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LEUKOTRIENE ANTAGONISTS
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Cromolyn sodium
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IMMUNE MODULATION THERAPY
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Cromolyn sodium • for asthma – Inhalation • for allergic rhinitis – Nasal
Mechanism: “mast cell stabilizer”
BUT, other (more effective) “mast cell stabilizers” do not have the anti-asthmatic effects of cromolyn.
Cromolyn may also inhibit T-cells and eosinophils. Also used for mastocytosis (too many mast cells) and various other inflammatory conditions (e.g. gastrointestinal)
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IMMUNE MODULATION THERAPY
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Omalizumab (Xolair®) Asthma – INJ (SQ every 2-4 weeks) -not for acute attacks
Mechanism: IgG1 monoclonal antibody that selectively binds to free human immunoglobulin E (IgE) in the blood and interstitial fluid. Blocks type I hypersensitivity reactions. Adverse Effects: BLACK BOX: anaphylaxis (0.1-0.2%)
Drug Interactions: Avoid combination with other immunosuppressants or use of live vaccines
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IMMUNE MODULATION THERAPY
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Mepolizumab (Nucala®) – Approved Nov 2015 Asthma – INJ (SQ once every 4 weeks) -not for acute attacks
IMMUNE MODULATION THERAPY
Adverse Effects: Hypersensitivity, infections (immunosuppression: herpes zoster, parasites)
Mechanism: IgG1 monoclonal antibody that selectively binds to (neutralizes) IL-5 and blocks IL-5 signaling and interferes with eosinophils.
Interleukin-5 (IL-5) Recruitment and activation
Inflammation and chronic airway changes
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Alkylamines (nonselective) Brompheniramine Chlorpheniramine Dexbrompheniramine Dexchlorpheniramine Triprolidine
Ethanolamines (nonselective) Carbinoxamine Clemastine Diphenhydramine Doxylamine
Phenothiazines (nonselective) Promethazine
Piperazines (nonselective)
Chlorocyclizine Hydroxyzine
(peripherally selective) Cetrizine (Zyrtec®) Levocetrizine (Xyzal®)
Piperidines (nonselective)
Cyproheptadine (peripherally selective)
Loratidine (Claritin®) Desloratidine (Clarinex®) Fexofenadine (Allegra®)
ANTIHISTAMINES – Allergic rhinitis
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ANTIHISTAMINES
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H1: INFLAMMATON AND BRONCHOCONSTRICTION
vasodilation, vascular permeability, contraction of nonvascular smooth muscle
H2: gastric acid secretion (may be involved in cardiac stimulation)
H3: feedback inhibition in CNS, GI tract, lung, heart
3 Types of Histamine Receptors
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ANTIHISTAMINES
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PERIPHERAL USES FOR H1 BLOCKERS:
1. Allergic rhinitis: relieves rhinorrhea, sneezing, itchy eyes
2. Common cold: (palliative) dries out the nasal mucosa (Often combined with nasal decongestant and analgesics)
3. Allergic dermatoses: itching associated with insect bites ASTHMA OR COPD? No good evidence that these have efficacy
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ANTIHISTAMINES
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ANTIHISTAMINES
CENTRAL USES FOR H1 BLOCKERS:
4. Pre-anesthetic sedation in outpatient procedures For prevention of nausea and vomiting. Promethazine (Phenergan) is also used to inhibit salivary and bronchial secretions
5. Antiemetic: prevention or treatment of nausea and vomiting (Doxylamine with Pyridoxine)
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Neurogenic/Chemical Control of DYSPNEA/VENTILATION
+ COPD
‘sensation’ of dyspnea
Blocked by opioids (morphine)
Opioids can also be used as antitussives (cough suppressants)
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