FSRH Drug Interactions Flashcards
What is pharmacokinetics ?
Pharmacokinetic drug interactions occur when one drug alters the absorption, distribution, metabolism, or excretion of another, changing its bioavailability.
In terms of contraception what is the most important pharmacokinetic drug interaction and with forms of contraception does it tend to impact ?
Anything that induces cytochrome P450 this impact all oral contraception, all combined methods, the implant and EC
How does CHC and lamotrigine interact ?
combined hormonal contraception induces glucuronidation of lamotrigine and reduces lamotrigine exposure
What is the mnemonic for remembering key enzyme-inducing drugs that affect hormonal contraception?
“Cool People Prefer To Read Good Erotic Stories”
What drug does “Cool” stand for in the enzyme inducer mnemonic?
Carbamazepine – used for epilepsy and bipolar – moderate inducer
What drug does “People” stand for in the enzyme inducer mnemonic?
Phenytoin – used for epilepsy – moderate inducer
What drug does “Prefer” stand for in the enzyme inducer mnemonic?
Phenobarbital / Primidone – used for epilepsy – moderate inducers
What drug does “To” stand for in the enzyme inducer mnemonic?
Topiramate – used for epilepsy, migraine – moderate inducer
What drug does “Read” stand for in the enzyme inducer mnemonic?
Rifampicin / Rifabutin – used for TB/meningitis – potent enzyme inducers 🚨
What drug does “Good” stand for in the enzyme inducer mnemonic?
Griseofulvin – used for fungal infections – moderate inducer
What drug does “Erotic” stand for in the enzyme inducer mnemonic?
Efavirenz / Nevirapine – used for HIV – moderate inducers
What drug does “Stories” stand for in the enzyme inducer mnemonic?
St John’s Wort – herbal remedy for low mood – moderate inducer
When using Lamotrigine, which forms for contraception require the user to use condoms alongside ?
CHC, POP, implant
