Pain 3 & 4

synergy drug treatment

interaction of 2 or more drugs when their combined effect is greater than the sum of the effects seen when each drugs is given alone

• lower doses/drug used to create an effect(to reduce the side effect)

  • higher dose= more/higher chance of side effects

treatment at PNS

high efficacy if inflammation is present

• NSAIDs

• Glucocorticoids

• inflammation increases volume which increases pressure

• this increases pain due to pressure on nociceptors

• so if we decrease inflammation we decrease pain

treatment at CNS

• opioids→ potency(mg or mcg)

• tylenol(acetaminophen)

acetaminophen(Tylenol)

centrally(CNS) acting analgesic

• #1 for antipyretic

• synergy that combines into >600 combination medications e.g. opioid Tramacet

• not an anti-inflammatory(is not an NSAID)

Mechanism of action:

• many theories most common one→ believes it interferes with prostaglandins(PGs) but not at the peripheral level(making it not an anti-inflammatory)

• agonizes cannabinoid receptors which have an inhibitory affect on the brain

fever-pyrexia

is a hypothalamic non-specific response to pyrogens with the goal of responding to endogenous and exogenous threats both

• exogenous→ bacteria produced e.g. endotoxins

• endogenous→ inflammatory mediators e.g. cytokines

• aim is to destroy pathogen by high temperature

• high temperature increases Basal metabolic rate(BMR)

• decreases cellular function which can make fever a bad thing

• and can be uncomfortable

• because it is a non-specific response we need to find the threat

antipyretics

goal is to comfort patient, decrease Basal metabolic rate(BMR) , and decrease cellular function

Drugs:

• acetaminophen(Tylenol)→ 1st choice, best efficacy

• NSAIDs(Ibuprofens, ASA)→ antiinflammatory reduce cytokines(no ASA in pediatrics)

other Tx:

• treatment of the cause(e.g. infection)

• hydration→ patient hydration status needs to be checked

• congestion, cough, rhinitis

acetaminophen(Tylenol) as an antipyretic

1st choice, best efficacy

• MOA: induces hypothalamic→ peripheral vasodilation(inhibit PGE2) which leads to heat loss

• safe in pediatrics(mg/kg) and in pregnancy

NSAIDS(Ibuprofen and ASA) as an antipyretic

anti-inflammatories reduce cytokines which causes a decrease in pyrogenic stimuli

• remember NO ASA IN PEDIATRICS

antitussives

medications used to suppress or relieve coughing

• CNS depression of cough reflex

• however is not always desirable→ coughing= protective innate response

drugs:

• codeine(opioid)→ causes CNS sedation

• Dextromethorphan(Robituzel)→ non-opioid that causes some CNS depression

congestion treatment

adrenergic agonist(sympathomimetic)

• Sympathetic nervous system stimulation decreases nasal secretions

Drugs:

• Ephedrine

• Pseudoephedrine

cough reflex

protective mechanism that uses forceful loud expiration to help clear mucus and irritants from airways(review this flashcard)

• afferent impulses from the cough center are sent to the medulla

• vagus nerve→ stimulates mechano/chemoreceptors in the upper/lower airways

• efferent impulses to diaphragm/lungs/intercostals= cough

• anti-tussive work against this reflex

benylin(daytime)

contains acetaminophen and provides relief of

• sinus pain

• nasal congestion→ by decreasing sinus pressure

• headache→ if headache was cause by sinus pressure release in nasal congestion and sinus pressure

• fever→ antipyretic piece of acetaminophen

Benylin( nighttime)

most likely a 1st generation antihistamine added which makes a person sleepy

fast relief of:

• runny nose→ decreases when we decrease nasal congestion

• sneezing

• sinus pain

• nasal congestion

• headache

menthol as an analgesic

mechanism of action→ activates cold sensing receptors

• has cooling effect which gives sensory receptors the effect of being cool

• free nerve ending(receptor for hot and cold) activating them works on he gate control theory of pain

• sensation of coolness activated receptors closes the gate on the pain signaling

• inhibitory interneuron signal back and override the sensation of pain

Robaxacet

combination drug of acetaminophen and muscle relaxant

• Robax=muscle relaxant(methocarbamol)

• acet=acetaminophen

• Mechanism of action is unclear but it is a CNS depressant→ depressing CNS stimulation of the somatic nervous system

• Side effects: patient can be more sleepy, be careful of other CNS depressants

Robaxisal

combination drug of ASA and methocarbamol with some acetaminophen mixed in a

acts a muscle relaxant that helps relieve:

• pain sensation

• back and muscle pain

psychological addiction

change in behavior to have a substance as much as possible

4 C’s:

• cravings

• compulsions to use

• loss of control over use

• Use despite harmful consequences

chronic pain

causes in alteration in pain pathway but not the same way as acute pain

• repetitive and altered Sympathetic NS initiation of responses leads to chronic inflammation and chronic pain cycle

• increased inflammation leads to increased pain

complex regional pain syndrome(CRPS)

develops after injury or surgery

• The pain is way more intense than expected for the injury and lasts longer than normal healing time

• the pain triggers another response establishing a cycle of pain and swelling

  can lead to:

• allodynia→ painful response to a non-painful stimulus

• muscle pr joint stiffness

• skin changes to the injured area→ hair loss, temperature changes, colour changes

treatment of chronic pain

• cognitive behavioral therapy(CBT)

• physiotherapy

• Occupational therapy(OT)→ optimize ability of patient to live with injury

• CNS drugs→ but opioids are not the 1st line in chronic pain

drugs that decrease excitatory neurotransmitters(Tx for chronic pain)

Gabapentin(gabrone)

NMDA antagonists

inhibit glutamate from binding

• NMDA receptors binds glutamate which is an excitatory neurotransmitter

tx of chronic pain→ serotonin

some antidepressants will increase serotonin will be used to modulate pain

• serotonin=mood stabilizing neurotransmitter in the brain\

• it modulates pain endogenously

• balance is needed to optimize mood

• side effects of excessive use→ tachycardia, tachypnea