drug therapy in pediatrics
- highly sensitive due to immature organs
- adjust dosage based on WEIGHT or BSA (body surface area)
- PO route preferred
FDA pregnancy categories - A
- no evidence of risk
- in controlled human study
- e.g. thyroid H, folic acid, prenatal vitamins
FDA pregnancy categories - B,C D
some risks
FDA pregnancy categories - X
- human teratogen
- contraindicated
- e.g. warfarin, live vaccines, accutane
drug therapy during breast feeding
- can be excreted in breast milk
- little research done
- take drug w/ shorter half life
- take after breastfeeding
- worst case - switch to formula
drug therapy in geriatric patients
- physiologic age more impt than chronological age= individualize therapy (decreased physiologic function –> increased toxicity)
- likely to have multiple disorders – polypharmacy –> drug interactions/toxicity
- should include simple dosing regimens
- frequent plasma drug levels
Acetylcholine
- neurotransmitter of the PNS
- released by somatic NS & parasympathetic NS
- released by all preganglionic neurons
- degraded by acetylcholinesterase (AchE)
Norepinephrine
- released by sympathetic NS
- REuptake into nerve terminals – > stored in vesicles for reuse OR destroyed by MAO (monoamine oxidate)
epinephrine
- release by adrenal medulla
- into blood stream –> hepatic metabolism
receptors of PNS - cholinergic
- nicotinic - skeletal muscles (somatic)
- muscarinic - internal/target organs of parasympathetic NS (rest, relax, eliminate)
receptors of PNS - adrenergic
sympathetic NS
- alpha 1 - peripheral blood vessels = vasoconstriction/incr BP
- alpha 2 - CNS =
- beta 1 - heart
- beta 2 - lungs, liver, uterus
- dopamine
activation of muscarinic cholinergic receptors
elicits parasympathetic response in target organ
activation of nicotinic cholinergic receptors
causes contraction of skeletal muscle
effects of drugs on steps of synaptic transmission
- alter synaptic transmission
- receptor selectivity - nonselective have more side effects
- influence receptor activity on target cells - agonists or antagonists
drugs that affect cholinergic receptors
- muscarinic agonists (cholinergics)
- muscarinic antagonists (anticholinergics)
- cholinesterase inhibitors
- neuromuscular blockade
muscarinic agonists (cholinergics)
- parasympathomimetic agents = mimic parasympathetic
- stimulate activity of target cells
- mimic action of Ach
Ex. Bethanechol (urecholine)
1. constrict iris sphincter (mitosis)
2. ↓ HR
3. bronchoconstriction; ⇡secretion
4. ⇡saliva, GI secretion, ⇡ motility, defecation
5. ⇡ sweating
Bethanechol (urecholine)
- cholinergics
MOA - activates muscarinic cholinergic receptors
No effect on nicotinic cholinergic receptors
Indicated for: urinary retention in post-op or part
SEs - ↓ HR, bronchoconstriction, cramping/diahrrea
Contraindicated for asthma pt
NI: ck HR, measure output
muscarinic antagonists (anticholinergics)
- parasympatholytic drugs = inhibit parasympathetic system (act like sympathetic)
- bind to muscarinic cholinergic receptors & inhibit activity of target cells.
- block the action of Ach at receptors
Effect:
eyes: mydriasis (dilate)
⇡ HR
bronchodilation
↓ saliva, ↓ motility
↓ emptying (promotes urine retention)
↓sweating
Atropine
anticholinergic
Side effects: eyes: photophobia, blurred vision, ⇡ IOP ⇡ HR bronchodilation dry mouth, constipation urinary retention no sweating, so at risk for hyperthermia / hot / red skin
Nursing implications & pt ed: anticholinergics
- drink water
- sunglasses
- intake of fiber (for constipation)
- show how to check pulse (for tachycardia)
cholinesterase inhibitors
- degrade cholinesterase, so more ACh is allowed
1. reversible
2 irreversible
myasthenia gravis
autoimmune disease that destroys ACh receptors
- s/sx muscle weakness & fatigue; eyelid droops; diplopia;
myasthenia crisis: sudden exacerbation of s/sx = respiratory weakness, needs ventilator
diagnose w/ anti cholinesterase test - short term, quick acting - if symptoms subside = make diagnosis = therapy is Neostigmine
reversible cholinesterase inhibitors
MOA - prevent degradation of ACh by AChE
⇡ ACh transmission at all cholinergic receptors
SE: cholinergic OD (crisis) - excessive stem of all cholinergic receptors
- ↓ HR
- muscle weakness – respiratory failure
Ex. Neostigmine
Antidote: ATROPINE, intubation & mechanical ventilation
irreversible cholinesterase inhibitors
- long duration & toxic effects
- puts pt into cholinergic crisis (excessive muscle & CNS stimulation)
- caused by insecticides, nerve gas, chemical weapons
- antidote: ATROPINE
