Immunopharm - Antihistamines and Migraines Flashcards
A migraine is a ___ headache. The inflammatory response spreads along the ___ system and arrives in the ___ ___ ___ and other areas to convey pain.
A migraine is a neurovascular headache. The inflammatory response spreads along the trigeminovascular system and arrives in the trigeminal nucleus caudalis and other areas to convey pain
Histamine:
Derived from ___ of ___, catalyzed by L-___ ____. Once formed it is stored or inactivated by ___-N-____ (in the CNS) or diamine oxidase (resulting in ____)
Histamine:
Derived from decarboxylation of histidine catalyzed by L-_histidine decarboxylase_. Once formed, it is stored or inactivated by histamine-N-_methyltransferase_ (in the CNS) or diamine oxidase (resulting in deamination)
Histamine:
- Where is it stored? Speed of turnover?
- Where does it have rapid turnover?
Histamine:
- Stored in mast cells and basophils with slow turnover
- Rapid turnover in neurons and enterochromaffin-like cells in the gastric mucosa
Histamine:
The allergen stimulates __ cells to produce ___ antibodies that then bind to ___ receptors on mast cells and basophils. This causes _____ and further allergen binding causes ___ of __/___ receptors producing degranulation (____ release)
Histamine:
The allergen stimulates B cells to produce IgE antibodies that then bind to Fc receptors on mast cells and basophils. This causes sensitization and further allergen binding causes crosslinking of IgE/Fc receptors producing degranulation (histamine release)
Function of Histamine:
- ____ responses: rhinitis and ___ (hives)
- 4 cardiovascular effects?
- What does it do to the airways?
Function of Histamine:
- Allergic response: rhinitis and urticaria
- CV: vasodilation, increased vascular permeability, injection produces a triple response (red spot/flare/wheal), and increase force of contraction of the heart
- Causes bronchoconstriction
Function of Histamine:
- Increases ___ ___ secretion
- Causes itch and potential ____ (severe hypotension, bronchoconstriction, and ____ swelling)
Function of Histamine:
- Increases gastric acid secretion
- Causes itch and potential anaphylaxis (severe hypotension, bronchoconstriction, and epiglottal swelling)
Histamine receptors:
H1:
- Distribution?
- Function?
Function of Histamine:
H1:
- In smooth muscle, vascular endothelium, and brain
- Bronchoconstriction, separation of endothelial cells (hives), pain, and itching
Histamine Receptors:
H2:
- Distribution?
- Function?
Histamine Receptors:
H2:
- Gastric mucosa, cardiac muscle, and brain
- vasodilation and stimulation of gastric acid secretion
Histamine Receptors:
H3:
- Distribution?
- Function?
Histamine Receptors:
H3:
- CNS and some PNS (autoreceptor in the PNS)
- Decreases NT release: histamine, ACh, NE, 5-HT
Histamine Receptors:
- All receptor subtyptes are ___ ____ ___.
- H1 receptors activate __ ___ that convert ____ to IP3 and ___ and are primarily involved in ___ and ___.
Histamine Receptors:
- All receptor subtypes are G protein couples
- H1 receptors activate G proteins that convert phosphatidylinositol to IP3 and DAG and are primarily involved in inflammation and allergy
Histamine Receptors:
- H2 receptors linked through G proteins to increase ___ with its primary function to regulate ___ ___ ___.
- H3 receptors function as ____ ____ in the CNS and PNS
Histamine Receptors:
- H2 increase cAMP and regulate gastric acid secretion
- Function as feedback inhibitors
3 strategies to inhibit histamine’s actions?
a. Administer drugs to counter pathology (Ep for aniphylaxis)
b. Prevent mast cell degeneration - cromolyn
c. Use Histamine receptor antagonists
H1 receptor antagonists:
- All agents are ___, ___, inhibitors.
- They all ___ the effects at H1 receptors and thus are useful in treating?
- What are the NOT effective in treating?
H1 receptor antagonists:
- All agents are reversible, competitive, inhibitors
- They all attenuate the effects at H1 and are good for allergic reactions, rhinitis, urticaria, itch, and flare
- DRUGS NOT EFFECTIVE FOR BRONCHOCONSTRICTION
H1 receptor antagonists:
First vs. Second generation Antagonists:
- First generation are highly ___ soluble and distribute to the ___ whereas second do not.
- First generation drugs produce ___ and ___ and exhibit some anti-_____ activity. Second generation in comparison?
H1 receptor antagonists:
First vs. Second generation Antagonists:
- First generation are highly lipid soluble and distribute to the CNS whereas second do not
- First generation drugs produce drowsiness and sedation and exhibit some anti-_muscarinic_ activity. Second generation has no anti-muscarinic activity and much less drowsiness/sedation
H1 receptor antagonists:
First vs. Second generation Antagonists:
- Why dont second generation drugs readily penetrate the CNS?
- Example of a girst generation drug with anti-muscarinic activity? Uses?
H1 receptor antagonists:
First vs. Second generation Antagonists:
- Dont penetrate because they are ionized at pH=7.4 and they are highly bound to albumin
- 1st generation: meclozine –> antiemetic or some antiparkinsons
First generation H1 receptor Antagonists:
- 5 drugs?
- Absorption? Distribution? Metabolization?
First generation H1 receptor Antagonists:
- Diphenhydramine, chorphenamine, dimenhydrinate, hydroxyzine, and promethazine
- Well absorbed, widely distributed (even to CNS), and extensively metabolized
First generation H1 receptor Antagonists:
- The major side effect? Which drug thus is best and why?
- What are the anticholinergic SE?
- Other SE?
First generation H1 receptor Antagonists:
- Major SE: sedation - chlorphenamin is best because its the least sedating
- Anticholinergic SE: dry mouth, cough, urinary retention, and blurred vision
- Other SE: loss of appetitie, N/V, dizziness, fatigue, tremor, hypersensitivity reactions
First generation H1 receptor Antagonists:
Dimenhydrinate and diphenhydramine have a ___ therapeutic index and often are used ____ as OTC ____.
First generation H1 receptor Antagonists:
Dimenhydrinate and diphenhydramine have a low therapeutic index and are often used recreationally as OTC hallucinogens
Second Generation H1 Receptor Antagonists:
- Drugs?
- Absorption? Distribution? Metabolism?
- SE?
Second Generation H1 Receptor Antagonists:
- Cetirizine, loratedine, desloratadine, and fexofenadine
- Well absorbed; no distribution to CNS; CYP450
- Minimal SE: sedation/drowsiness –> no anticholinergic effects
Therapeutic Actions of Antihistamines:
- Acute ____ reactions
- Reduce ___
- Diminish symptoms of ___ and ___
- What first generation drugs are used for prophylaxis and treatment of motion sickness?
Therapeutic Actions of Antihistamines:
- Acute allergic reactions
- Reduce itching
- Diminish symptoms of cold and flu
- Motion sickness: diphenhydramine and promethazine
Therapeutic Actions of Antihistamines:
- What can diphenhydramine reduce?
- What can promethazine treat?
- First generation drugs are used for ___ and occassionally for ___ but routine use is not recommended.
Therapeutic Actions of Antihistamines:
- Diphenhydramine can reduce Parkinson’s symptoms
- Promethazine can treat nausea and vomitting
- 1st generation: somnolence and occasionally insomnia but shouldnt be used long term
H2 receptor antagonists:
- Drugs?
- Function?
H2 receptor antagonists:
- Cimetidine, famotidine, ranitidine, and nizatidine
- Inhibits stomach acid production
H2 receptor antagonists:
- Indicatons?
- Why is cimetidine no longer recommended?
Therapeutic Actions of Antihistamines:
- Indications: GERD, peptic ulcer disease, and heartburn
- Cimetidine: no longer recommended because it is used as a suicide substrate for CYP 3A4 and potential toxicity of concurrently ingested drugs that are metabolized by this CYP isoform
5-Hydroxytryptamine (serotonin):
- Mainly found where?
- 80% is in what cells?
- Mainly metabolized to ____ by the ___. This is used to determine 5HT levels in the body via urine analysis.
5-Hydroxytryptamine (serotonin):
- Found in gut, platelets, and CNS
- 80% in enterochromaffin cells in the gut
- Mainly metabolized to 5-HIAA by the liver
5-Hydroxytryptamine (serotonin):
Has three fates after synthesis, what are these?
5-Hydroxytryptamine (serotonin):
a. Storage (gut)
b. Rapid inactivation by MAO
c. Precursor for melatonin in pineal gland
5-Hydroxytryptamine (serotonin) receptors:
- 5HT1A/1B: thought to be ____ receptors in the ___ nuclei and _____.
- 5HT2A: contributes to ____ aggregation in the ___, ___, blood vessels, GI, and ____ muscle
- 5HT1D: produces ___ in the ___
5-Hydroxytryptamine (serotonin) receptors:
- 5HT1A/1B: thought to be auto-receptors in the raphe nuclei and hippocampus
- 5HT2A: contributes to platelet aggregation in the CNS, PNS, blood vessels, GI, and smooth muscle
- 5HT1D: produces vasoconstriction in the brain
5-Hydroxytryptamine (serotonin) receptors:
- 5HT2A/3/4: is involved in ___ excitation in the ___, ___, and ___
- 5HT2A/2B: ____ smooth muscle in the ___, PNS, ___ ___, and GI
5-Hydroxytryptamine (serotonin) receptors:
- 5HT2A/3/4: is involved in neuronal excitation in the CNS, PNS, and GI
- 5HT2A/2B: contracts smooth muscle in the CNS, PNS, blood vessels, and GI
5-Hydroxytryptamine (serotonin) receptors:
- All of the roles of 5HT2A?
- Which receptor produces vasoconstriction in the brain?
- Which receptors are auto-receptors?
5-Hydroxytryptamine (serotonin) receptors:
- 5HT2A: platelet aggregation, neuronal excitation, and contraction of the smooth muscle
- 5HT1D - vasoconstriction in brain
- 5HT1A/1B - autoreceptors (raphe nuclei and hippocampus)
5-Hydroxytryptamine (serotonin) receptors:
- Which receptors produce neuronal excitation?
- Which receptors contracts smooth muscle?
5-Hydroxytryptamine (serotonin) receptors:
- 5HT2A/3/4 - neuronal excitation
- 5HT2A/2B - contracts smooth muscle
Actions of Serotonin:
- ___ aggregation
- Contraction of vascular smooth muscle where?
- Function on the heart?
Actions of Serotonin:
- Platelet aggregation
- Contraction of vascular smooth muscle in splanchnic, renal, pulmonary, and cerebral vasculatures
- Acts as a positive inotrope (increases strength) and positive chronotrope (increases HR) on the heart
Actions of Serotonin:
- Stimulaes what part of the GI? Inhibits what part?
- Sensitizes small diameter ___ neruons
- What “cerebral” functions does it effect?
Actions of Serotonin:
- Stimulates SI motility, inhibits stomach smooth muscle
- Sensitizes sensory neurons
- Affects sleep, cognition, temperature regulation, and motor activity
Actions of Serotonin:
- Drugs that block 5HT2C are associated with?
- Migraine = complex _____ disorder. Key features are ___ (often ____ and throbbing) and associated with ___, as well as sensitivity to __, ___, and exacerbation with head movements
Actions of Serotonin:
- Block 5HT2C: wt gain because generally serotonin inhibits stomach smooth muscle and decreases appetite. By blocking this inhibition - stimulating appetite
- Migraine = complex neurobiological disorder. Key features are HA (often unilateral and throbbing) and associated with nausea as well as sensitivity to light, sound, and exacerbations of heat movements
Overview of migraines:
- In about 20-30% of subjects, headache is preceeded by ___ ( visual, ___, or ___ deficits). There is often a strong ___ component.
- The key pathway for the pain is the __-_____ input from the ___ vessels. These nerves pass through the ___ ganglion and synapses, and project though the _____ tract and form synapses in the ___.
Overview of migraines:
- Preceeded by aura (visual, motor, or speech deficits). There is often a strong genetic component
- The key pathway for the pain is the tri-geminovascular input from the meningeal vessels. These nerves pass through the trigeminal ganglion and synapses, and project through the quintothalamic tract and form synapses in the thalamus
Phases of a migraine attack:
What are the 5 phases?
Many dont have which?
Phases:
a. Prodrome
b. Aura phase
c. Migraine headache
d. Resolution phase
e. Migraine hangover
– Many dont have prodrome or postdromes
Phases of a migraine attack:
- Prodrome: vague ___ or ___ symptoms as much as ___ (time) prior
- Aura - what does this involve? Length of time?
Phases of a migraine attack:
- Prodrome: vague vegetative or affective symptoms as much as 24 hours prior
- Aura: focal neurological symptoms - up to one hour long preceeding the migraine headache
Phases of a migraine attack:
- Migraine headache: within _ __ (time) of resolution of the aura, typical migraine (often with ___) occurs for up to ___ hours
- Resolution phase is characterized by ___ ___
- Migraine hangover: duration? What does it involve?
Phases of a migraine attack:
- Migraine headache: within 1 hour of resolution the aura, typical migraine (often with throbbing) occurs for up to 72 hours
- Resolution phase is characterized by deep sleep
- Migraine hangover: up to 24 hours after with fatigue, maliase, and transient return of pain following cough/sudden head movement
CSD:
- What does CSD stand for?
- What is it the cause of?
CSD:
- Cortical Spreading Depression
- The cause of migraine aura
Cortical Spreading Depression:
- Wave of ___ - lasting electrophysiological ____ followed by a wave of ___ ___ of neuronal activity usually in the cerebral ____.
- CSD upregulates a variety of genes coding for?
- Increased metalloproteinases leads to ___ of BBB allowing ___, ___, and ___ to reach the dural perivascular ___ afferents.
Cortical Spreading Depression:
- Wave of short lasting electrophysiological hyperactivity followed by a wave of prolonged inhibition of activity in the cortex
- Upregulates genes for: COX-2, TNF, IL-1, galanin, or metalloproteinases
- Leads to leakage of BBB allowing K+, NO, and adenosine to reach perivascular trigeminal afferents
Migraine:
- The aura phase is a primarily ____ phenomenon as it may activate the ____ fibers through the ___.
- Nonspecific treatment of acute attack migraine?
- Specific treatment of acute attack migraine?
- What is the first choice combination as analgesic and antipyretic?
Migraine:
- The aura phase is a primarily cortical phenomenon as it may activate the trigeminal fibers through the dura.
- Nonspecific: NSAIDs, anti-emetics, opioids, corticosteroids, and dopamine antagonists
- Specific: ergotamine, DHE, and triptans
- Aspirin, acetaminophen, and caffiene
Triptans:
- Act at what receptor? Subtypes?
- Drug examples?
Triptans:
- Act at 5HT1 –> 5HT1B and 5HT1D
- Sumatripan and zolmitriptan
Triptans:
Two proposed MOA:
a. Direct ____ action on ______ blood vessels by binding ___.
b. _____ inhibition on ___ neurons by blocking ____ gene regulated peptide. This is a _____ NT
Triptans:
Two MOA:
a. Direct vasoconstrictive action on intracrania blood vessels by binding 5HT1
b. Presynaptic inhibition on sensory neurons by blocking calcitonin gene regulated peptide. This is a proinflammatory NT
Triptans:
- Indications? Not useful for?
- Administration?
- SE?
Triptans:
- DRUG OF CHOICE for acute treatment of migraine; not for long term or prophylaxis
- Subcutaneous injection, orally, or nasal spray
- SE: nausea, malaise, dizziness, weakness, dry mouth, paresthesia, pain at injection site
Triptans:
- Rare SE?
- Who should be screened prior to administration of sumatriptan/zolmitriptan?
Triptans:
- Rare: coronary artery spasm, ischemia, and arrhythmias
- Screened: those at risk for coronary heart disease, diabetes, obesity, severe uncontrolled hypertension, or hypercholesterolemia
Triptans:
Contraindications:
- History of?
- Those with what vascular diseases?
- Uncontrolled ____
- Taking ____.
- Naratriptan is not for patients with severe ___ or ___ disease
Triptans:
Contraindications:
- History of coronary artery disease
- Those with cerebrovascular or peripheral vascular disease
- Uncontrolled hypertension
- Taking MAOIs
- Naratriptan: not for hepatic or renal disease
Ergot Alkaloids:
- Drug examples?
- Mechanism is attributed to ___ action at ___.
Ergot Alkaloids:
- Ergotamine and dihydroergotamine
- Mechanism is attributed to agonist action at 5HT1
Ergot Alkaloids:
- What are these for? Not for?
- Administration of ergotamine?
- Administration of DHE?
Ergot Alkaloids:
- For moderate to severe migraine; not for prophylaxis
- Ergotamine: oral, IV, or IM
- DHE: IV
Ergot Alkaloids:
- What increases rate/extension of absorption?
- This is best when given in ___ phase.
- Major SE?
Ergot Alkaloids:
- Caffiene increases rate of absorption
- Best in prodromal phase
- Major SE: nausea, vasoconstriction with ischemia/leg weakness/muscle pain
Ergot Alkaloids:
Contraindications? (7)
Ergot Alkaloids:
Contraindications
a. Pregnancy: stimulate uterus and restric uterine BF
b. Coronary/peripheral artery disease
c. Liver/renal disease
d. stroke
e. Severe hypertension
Prophylactic Agents:
Name some categories.
Prophylactic agents:
a. Beta blockers
b. Antidepressants
c. Ca++ antagonists
d. Anticonvulstants
e. NSAIDs
f. Methysergide
g. 5HT antagonists
Amitriptyline:
- Class of drug?
- MOA?
- SE?
Amitriptyline:
- TCA
- 5HT/NE reuptake inhibitor and antagonist at some 5HT/histamine receptors
- SE: sleepy, dry mouth, and can induce hepatotoxicity
Propranalol
- Class?
- Used for treatment of ___, anxiety, panic, ___ ___, and cluster HA prophylaxis
- MOA: blocks action of ___ and ___ on what receptors?
Propranalol
- Non-selective beta blocker
- Used for treatment of hypertension, anxiety, panic, migraine prophylaxis, and cluster HA prophylaxis
- MOA: blocks action of epinepherine and NE on both beta1 and beta2 receptors
Topiramate:
- Class of drug?
- Used for wt loss in combination with ___, treatment of ____ in kids/adults, and most frequently prescribed for ___ ___.
- SE?
Topiramate:
- Anticonvulsant
- Wt loss in combo with phentermine, treatment of epilepsy in kids/adults, but most frequently for migraine prophylaxis
- SE: parasthesia, upper RTI, diarrhea, and nausea
Methysergide:
- Class?
- Antagonist at ____ receptor. Prevents or decreases __ and ___. Inhibits release of ___ from ___ cells. Antagonist at ___ alters patients feeling of satiety.
- Metabolism?
Methysergide:
- Ergot Alkaloid
- Antagonist at 5HT2B receptor. Prevents or decreases pain and frequency. Inhibits release of histamine from mast cells. Antagonist at 5HT2C alters feelings of satiety
- Metabolised by CYP450 3A4
Methysergide:
- Short term SE?
- Long term SE:
Methysergide:
- Short: nausea, vasoconstriction with ischemia/leg weakness/muscle pain
- Long: retroperitoneal, heart, or lung fibrosis
Methysergide:
Contraindications?
Methysergide:
Pregnancy, coronary artery disease (may cause MI), peripheral vascular disease, hypertension, hepatic or renal impairment
Cyproheptadine:
- Acts at what receptors?
- For ___ reactions, nightmares, ____ syndrome, management of ______ from ___ producting carcinoid tumor.
Cyproheptadine:
- Acts at H1, 5HT2A/2B/2C
- For allergic reactions, nightmares, serotonin syndrome, management of hyperseritonemia from serotonin producing carcinoid tumor
Ondansetron:
- Acts at what receptor?
- Indication?
Ondansetron:
- Acts at 5HT3 receptor (antagonist)
- For nausea following chemotherapy/post operative as well as vomitting: acts as antiemetic
Ondansetron:
- MOA: decreases activity of the ___ which deactivates ___ center in medulla oblongotta and ___ receptor in ___ receptor trigger zone
- SE?
- Metabolism?
Ondansetron:
- MOA: decreases activity of the vagus which deactivates vomitting center in the medulla oblongotta and serotonin receptor in the chemo-receptor trigger zone
- SE: HA, dizziness, constipation
- Metabolism: CYP450