NEET MDS Lessons
Pharmacology
Treatment modifications to consider if there are concerns regarding vasoconstrictors
- Monitor blood pressure and heart rate preoperatively
- Minimize administration of epinephrine or levonordefrin
- Monitor blood pressure and heart rate 5 min after injection
- May re-administer epinephrine or levonordefrin if blood pressure and heart rate are stable
- Continue to monitor as required
- Consider limiting epinephrine to 0.04 mg, levonordefrin to 0.2 mg
- Avoid epinephrine 1:50,000
- Never use epinephrine-impregnated retraction cord
Phenobarbital (Luminal): for generalized tonic-clonic and partial seizures (not used for absence seizures)
Mechanism: enhances GABA inhibition (↑ open time of Cl channels in presence of GABA)
Side effects: sedation, ataxia, cognitive impairment, induction of hepatic microsomal enzymes
Procaine penicillin Procaine penicillin is a combination of benzylpenicillin with the local anaesthetic agent procaine. This combination is aimed at reducing the pain and discomfort associated with a large intramuscular injection of penicillin.
Indications
respiratory tract infections where compliance with oral treatment is unlikely ,syphilis, cellulitis
Stages of anesthesia
Stage I
Analgesia
Still conscious but drowsy
Stage II
Excitement stage
Loss of consciousness, however, irregular ventilation may be present which affects absorption of inhalation agents.
Reflexes may be exaggerated.
This is a very dangerous stage
Stage III
Surgical anesthesia
Loss of spontaneous movement
Regular, shallow respiration
Relaxation of muscles
Stage IV
Medullary paralysis
Death
Stimulants:
Amphetamines: amphetamine is a substrate of serotonin and NE uptake transporters so in cytoplasm, it competes for transport into storage vesicles → ↑ [ ] in cytoplasm then excess amines bind to membrane transporter and are transported out of cell
Drugs:
a. Dextroamphetamine: psychomotor stimulant (↓ fatigue), short-term weight loss, prevents narcolepsy
b. Methylphenidate (Ritalin): prevents narcolepsy, treatment for ADD and ADHD
c. Methamphetamine: psychomotor stimulant, abused widely (cheap, easy to make)
Side effects:
a. CNS: euphoria, anxiety, agitation, delirium, paranoia, panic, suicidal/homicidal impulses, psychoses, tolerance (develops rapidly to most CNS effects), physical dependence (not clinically relevant)
b. CV: headache, chills, arrhythmias and HTN (may be fatal)
Ciprofloxacin : Ciprofloxacin is bactericidal and its mode of action depends on blocking of bacterial DNA replication by binding itself to an enzyme called DNA gyrase
Ciprofloxacin is a broad-spectrum antibiotic that is active against both Gram-positive and Gram-negative bacteria.
Enterobacteriaceae, Vibrio, Hemophilus influenzae, Neisseria gonorrhoeae
Neisseria menigitidis, Moraxella catarrhalis, Brucella, Campylobacter,
Mycobacterium intracellulare, Legionella sp., Pseudomonas aeruginosa,
Bacillus anthracis - that causes anthrax
Weak activity against: Streptococcus pneumoniae,
No activity against: Bacteroides, Enterococcus faecium, Ureaplasma urealyticum and others
It is contraindicated in children, pregnancy, and epilepsy.
Ciprofloxacin can cause photosensitivity reactions and can elevate plasma
theophylline levels to toxic values. It can also cause constipation and sensitivity to caffeine.
Dosage in respiratory infections is 500-1500 mg a day in 2 doses.
PHARYNGEAL DEMULCENTS
Administered in the form of lozenges, cough drops and cough linctus.
Produce soothing action on throat directly and by increasing the flow of saliva and provide symptomatic relief from dry cough.
EXPECTORANT
Expectorants are the drugs which increase the production of bronchial secretion and reduce its viscosity to facilitate its removal by coughing.
ANTITUSSIVES
They are central cough suppressants and act centrally to raise the threshold of cough centre and inhibit the cough reflex by suppressing the coordinating cough centre in the medulla oblongata.
Codeine - it depresses cough centre but is less constipating and abuse liability is low.
Pholcodeine is similar to codeine in efficacy and is longer acting. It has no analgesic or addicting property.
Noscapine is another opium alkaloid of benzylisoquinoline group. It is used as antitussive with no analgesic and drug abuse or drug dependence property.
Dextromethorphan is a synthetic compound and its dextroisomer is used as antitussive and is as effective as codeine
Pipazethate is another synthetic compound of phenothiazine category used as antitussive with little analgesic and sedative properties.
ANTIHISTAMINICS
They do not act on cough centre but provide relief due to their sedative and anticholinergic action.
BRONCHODILATORS
Bronchodilators are helpful in individuals with cough and bronchoconstriction due to bronchial hyperreactivity. They help by improving the effectiveness of cough in clearing secretions.