Respiratory stimulants: types, complete discussion on indications, contraindications, assessment, patient notes and examples of stimulants both central and respiratory

1. Dr. KRVS Chaitanya
RESPIRATORY
STIMULANTS
(analeptics)
Dr. Koppala RVS Chaitanya
Department of Pharmacology

2. Dr. KRVS Chaitanya
RESPIRATORY STIMULANTS (analeptics)
 Stimulate respiration and have resuscitative value in coma and fainting.
 Stimulate respiration in convulsive doses
 May get convulsion while in coma
 Mechanical support to respiration improves respiration.
Indications:
 Hypnotic drug poisoning (until mechanical)
 Suffocation on drowning
 Acute respiratory insufficiency
 Apnoea in premature infant
 Failure to ventilate post anesthesia
DOXAPRAM:
 Promoting excitation of CNS
 Stimulated by aortic body chemoreceptors
 Carotid body chemoreceptors
I.v. infusion of doxapram abolish episodes of apnoea in premature infant with side effects of
 Spasticity
 Hypertension
 Tachycardia
 Tremors
 Hyperactive reflexes
Mechanism of actions:
1. Potassium channel blocker
Doxapram act on potassium channel in carotid bodies
Next sense low concentration of potassium, oxygen and relays into CNS
Stimulate respiratory rate
Doxapram blocks potassium channel mainly BK Channels by depolarizing the ventral
groups of Calcium channel by increasing neurotransmitter release
2. AMPakines:

3. Dr. KRVS Chaitanya
Bind to AMPA receptors in PreBotzinger complex part of ventral respiratory group
(VRG)
Stimulate AMPA receptor ligand glutamate moiety
Opens allows Na+ ions inside the cell
Causes depolarization
Starts signal transduction
Stimulate respiration
3. Serotonin receptors agonists:
Serotonin receptor is GPCR
Activation of Gs Protein
Stimulates c AMP
Initiates signal transduction with increase influx of Calcium ions.
4. Adenosine antagonists
Caffeine with decrease respiratory drive and stimulates respiratory drive by electrical
act on neurons.
Doxapram, Caffeine, Theophylline, Aminophylline
Indications:
 Asthma
 Respiratory depression
 Apnoea of prematurity
Side effects:
 Muscle tremors
 Agitation, anxiety, irritability, insomnia
 Hypertension, heart palpitations, tachycardia, ECG abnormalities
 Gastrointestinal disturbances: nausea, vomiting, diarrhea

4. Dr. KRVS Chaitanya
 Theophylline overdose: arrhythmias, seizures
 Caffeine (high doses to premature infants): intracranial hemorrhage
Contraindications:
 Arteriosclerosis, cardiovascular disease, hypertension
 Pregnancy and breastfeeding
 History of seizures
 Hepatic or renal disease
 Theophylline: drug interactions with beta blockers, phenytoin, beta adrenergic
agonists, antidepressants, cimetidine, ciprofloxacin, tobacco smoke, and marijuana
Assessment and monitoring
Assessment
 Vital signs, especially respiratory rate; SpO2, lung sounds
 Laboratory test results: renal and hepatic function
Monitoring
 Vital signs
 Serum drug concentration levels; not to exceed 20 mcg/mL
 Side effects
 Evaluate therapeutic response: improved airflow and decreased respiratory effort
Client education
 Purpose of medication: help them to breathe easier
 Take medication in the morning, with or without food
 Avoid taking at bedtime
 Avoid smoking, alcohol, and dietary sources of caffeine, like coffee, tea, soda, and
chocolate
 Side effects to report
 Nausea, irritability, anxiety, tachycardia, palpitations, insomnia, nausea
 If side effects are persistent or severe
 Symptoms of toxicity: dizziness, lightheadedness, fatigue, weakness, shortness of
breath
Respiratory stimulants, from a pharmacological perspective, are essential agents that augment
respiratory drive and enhance ventilation. Operating predominantly within the central
nervous system, these medications target respiratory centres located in the medulla oblongata,
a region vital for regulating breathing patterns. One prominent class of respiratory stimulants
encompasses drugs like doxapram and methylxanthines such as theophylline and caffeine.

5. Dr. KRVS Chaitanya
Doxapram directly stimulates respiratory centres, thereby increasing both the rate and depth
of breathing. Methylxanthines, by contrast, function as non-specific adenosine receptor
antagonists, provoking central respiratory stimulation alongside bronchodilatation. Clinically,
respiratory stimulants serve as crucial interventions in conditions characterized by respiratory
depression, including drug overdose, anesthesia-induced respiratory suppression, and chronic
respiratory ailments like chronic obstructive pulmonary disease (COPD). However, their
usage mandates careful consideration due to potential adverse effects such as tachycardia,
hypertension, and central nervous system excitation. In summary, respiratory stimulants play
a pivotal role in managing respiratory depression and augmenting ventilation. Yet, their
administration necessitates meticulous dosing and vigilant monitoring to mitigate potential
complications and ensure optimal patient outcomes.