ADME Flashcards
Meningitis and BBB
meningitis is inflammation of membranes (meninges) surronding spinal cord , integrity of BBBcan be comprimised
How to treat meningitis
Antibiotics that do not pass BBB
E.g Benzylpenicillin
Give two antiemetics and explain if they cross BBB or not
Domperidone and Metocloperamide both inhibits dopamine (dopamine receptor antagonist)
Metocloperamide cross BBB
Doperidone do not cross BBB
What are the pharmacokinetic characteristics and clinical uses of Propofol?
Propofol is an IV general anesthetic following a 2-compartment model. It is highly lipid-soluble, used for rapid induction of anesthesia with an onset of action within 20 seconds and a short duration of 5-10 minutes. Its elimination half-life is 2-30 hours, and it requires careful dosing to maintain anesthesia without prolonged effects.
What are zero-order kinetics in drug metabolism?
Zero-order kinetics occur when the rate of drug elimination is constant and does not change with increasing drug concentration. This happens when the drug-metabolizing enzymes are saturated. Classic examples include phenytoin and ethanol. Unlike first-order kinetics where elimination is proportional to the drug concentration, in zero-order kinetics, a constant amount of drug is eliminated per unit time.
What are the potential teratogenic effects of Phenytoin when used during pregnancy?
Phenytoin use during pregnancy can be associated with craniofacial abnormalities, hypoplasia of distal phalanges, growth and mental deficiency, collectively known as fetal hydantoin syndrome.
What are the risks of using Valproate during pregnancy?
Valproate is associated with a high risk of neural tube defects and can lead to learning difficulties in the child; it is considered highly teratogenic.
How does Carbamazepine compare with Phenytoin in terms of teratogenic risk during pregnancy?
How does Carbamazepine compare with Phenytoin in terms of teratogenic risk during pregnancy?
Firstline for tonic clonic seizures
Lamotigrine
Prevents these drugs during pregnancy depression
SSRI citolopram and setaline
Associates cardiac septal defects
What are the pharmacological actions of St. John’s Wort?
St. John’s Wort has SSRI-like actions and can increase serotonin levels in the brain, which may help improve mood and relieve symptoms of depression.
What is a major risk when combining St. John’s Wort with SSRIs?
The combination can lead to Serotonin Syndrome, a potentially life-threatening condition due to excessive serotonin levels.
How does St. John’s Wort affect drug metabolism?
It is an enzyme inducer, which can accelerate the metabolism of certain drugs, reducing their effectiveness.
Which drugs can have their effectiveness reduced by St. John’s Wort?
St. John’s Wort can reduce the effectiveness of oral contraceptives, anti-HIV drugs, and immunosuppressants like Ciclosporin.
What is the therapeutic window for lithium treatment?
The therapeutic window for lithium is narrow, typically 0.4-1 mmol/L, requiring close monitoring to avoid toxicity.
