nitrous oxide and carbamazepine Flashcards
What is nitrous oxide also known as
Laughing gas
Why is nitrous oxide used in dentistry
Used fro inhalation sedation in children and adult patients
What properties does nitrous oxide have
It has anaesthetic and analgesic properties
What effect does nitrous oxide have on the bodys reaction time
Slows down reaction time
What does the mechanism of action of nitrous oxide
May involve NMDA glutamate receptor blockade so produce its general anaesthesia effect
What effect can nitrous oxide have on opioid receptors
has the potential to stimulate opioid receptors to produce analgesia
What effect can long term arise of nitrous oxide have on the body
May megaloblastic anaemia and spinal cord degeneration
Describe the pharmacokinetics of nitrous oxide
Nitrous oxide is more soluble in water than nitrogen on its own is
Where is nitrous oxide preferably exchanged
Exchanged at the alveolar membranes of the lungs and readily enters the bloodstream to exert its effect
How can nitrous oxide affect respiration
- Reduced total volume
2. Increases respiratory rate
How can nitrous oxide affect on the heart
Mild effects on heart rate and pulmonary vascular resistance
How can nitrous oxide affect the renal and hepatic system
Reduced renal and hepatic blood flow
How can nitrous oxide affection on blood flow
Increases cerebral blood flow metabolism and intracranial pressure
What can carbamazepine be used for
- Anti-epileptic drug/anticonvulsant
- Neuropathic pain
- Bipolar disorder
Describe the pharmacodynamics of carbamazepine
Sodium channel blockade treats seizures
Narrow therapeutic index
What is the mechanism of action of carbamazepine
- Reduces excitability of neurones by sodium channel blockade
- Lowers presynaptic nerve response and inhibits post synaptic potential
- Binds to voltage-gated sodium channels and prevents action potentials firing
What can carbamazepine do in bipolar disorder
It increases metabolism of dopamine and increases transmission of GABA to treat mania an depressive symptoms
What is carbamazepine known as
Enzyme inducer
What do we mean by enzyme inducer
Means it potently induces the pathways of metabolism of numerous other drugs
this mean the second drug may have a lower effective dose
what should we do if carbamazepine is administrated with another drug
We may need to increase the dose of the other drug which may have metabolised due to carbamazepine
Where is carbamazepine metabolised
by the liver through the CYP P450 pathway
What happens to carbamazepine in the liver
Undergoes hepatic glucuronidation resulting in minor hydroxy metabolites and quinone metabolites
What induces carbamazepine metabolism and what does this mean
carbamazepine induces its own metabolism leading to enhanced clearance, reduced half-life and reduced serum levels
What is the half life of carbamazepine
12-17 hours
What are the common side effects of carbamazepine
- Drowsiness,
- dizziness,
- headaches,
- nausea,
- double vision,
- unsteadiness,
- memory/ concentration difficulties
What are the contra indications of carbamazepine
- Allergy
2, Heart disease - Porphyria
- Bone marrow disorders
In whom should we be cautious prescribing carbamazepine
Patients with:
- Cardiac disease
- Hx of haematological reactions to other drugs
- Absence/myoclonic seizures
- History of skin reactions
- Angle-closure glaucoma
What are the serious side effects of carbamazepine
- Agranulocytosis (rare/very rare)
2, Steven- Johnson syndrom e - Unusual bleeding/ bruising with mouth ulcers, high temp or sore throat
- Suicidal ideation/ psychosis
- Jaundice
- Muscle and joint pain, molar rash, breathing difficulties
Should we prescribe carbamazepine in pregnancy patients
yes we can
What can carbamazepine interact with
- Anticoagulants- warfarin, NOACs
- Antibiotics- clarithromycin, erythromycin
- Antifungals -fluconazole
- Antidepressants
- Cyclosporine
- HIV medication
- MAOIs
- St johns wort
- Alcohol
