Medchem Final Flashcards
What are the Three Severe toxicities of trimethylated oxazolidinedione
- Photophobia
- teratogenicity
- aplastic anemia
Basification of the urine with sodium bicarbonate is useful in cases of barbiturate poising.
Explain fully in terms of pKa & pH why this is so?
Barbiturates are weak acids with pKa of 8(7.4-8.5)
Under normal circumstances most of the parent drug(that gets filtered) is REABOSRBED from the kidney tubule where urine pH is 6, because its UNCHARGED.
At higher urine pH, due to basification, more drug is CHARGED so less is reabsorbed
What are five important features of a successful drug treating insomnia
- Reduced sleep LATENCY
- Increased sleep MAINTENANCE
- Increased sleep QUALITY
- Decreased next-day impairment
- Less tendency for habituation/dependence
What is the biological target for each drug?
Zaleplon
Ramelteon
Suvorexant
- alpha-1 subunit of GABAA receptor
- MT1/MT2 receptors
- Orexin 1/2 receptor
What is unusual about the tablet formulation of Zaleplon?
- Blue color (indigo carmine)
- Opacifer (titanium dioxide)
Present in tablet to provide alert if drink is “spiked”
Lamotrigine is a useful antiepileptic by virtue of its folate antagonism (T/F)
False
5,5’- Disubstituted barbiturates do not exhibit keto-enol tautomerism (T/F)
True
Pregabilin is poorly bioavailable because it saturates the intestinal uptake transporter (T/F)
False
2-SORA drugs are being developed for treating addiction (T/F)
False
In order to possess appreciable sedative-hypnotic activity a barbituric acid derivative must have a logP of 2-3 (T/F)
False
Narcolepsy in dogs led to the discovery of MT1 receptors that can be targeted to treat insomnia (T/F)
False
Valproate’s induction of glutamic acid decarboxylase contributes to its antiepileptic effects (T/F)
True
Primidone must undergo a decarboxylation event ot generate the active metabolite, PEMA (T/F)
True
The ultra-short duration of action of tiopenal is due to rapid hydrolysis in the brain (T/F)
False
The pH of fosphenytoin for injection is 12 (T/F)
False
What is a serious toxicity of Vinylgaba that delayed its approval by the FDA?
- psychoses
- depression
- visual field distrubances
A patient is taking lamotrigine and will be started on valproic acid. The dose of lamotrigine should be?
(Increased/Decreased/unchanged)
Decreased
What is the mechanism of Valproate?
Valproate is an INHIBITOR of the UGT- enzymes that are directly N-glucoronidate lamotrigine to metabolically inactive drug.
What is Sleep Latency?
The TIme period until one falls asleep
Zaleplon is marketed as the best drug for sleep latency. How does the pharmacokinetics make this argument?
Zaleplon’s short tmax (rapid onset) is the key pharmacokinetic parameter
What is the configuration of Ramelteon at is chiral center
S
N-1: methyl group
contributes to both increased logP and increased pKa
higher pKa means that more of the drug is UNIONIZED at physiological pH facilitating it crossing BBB
C-5:
increased carbon load UNSATATURATION elevate logP above the values for sedative hypnotics (1.5-2).
Increased lipophilicity and higher pKa
How are ESL & OXC an advance over the prototypic drug Carbamazepine?
OXL & SLC avoid formation of Epoxide intermediate–> improve side effect profile and tolerability
OXC & SLC weaker P450 inducers than CBZ–>fewer drug interactions
Ezcopiclone is a good choice of hypnotic to increase sleep maintenance (T/F)
True
Barbiturates cause acute intermittent porphyria (T/F)
False
Flumazenil antagonizes the sedative effects of the z-drugs (T/F)
True
Tiagabine is a GABA-mimetic (T/F)
T/F
The major GABA receptor in the brain is composed of alpha1, beta2, gama2 subunits (T/F)
True
Diazepam forms the active metabolite, oxazepam and temazepam (T/F)
True
CBZ’s unusual carbamyl substituent is believed to be responsible for the drugs side-effects (T/F)
False
Almost none of the dose of phenobarbital is excreted unchanged in the urine (T/F)
False
1,5,5’-Trisubsitituted barbiturates do not form lactim tautomers (T/F)
False
The 3C’s describe the symptoms of barbiturate overdoes (T/F)
False
The mechanism of vinylgaba’s suicide inhibition of GABA-T involves radical intermediates (T/F)
False
Suveroxant is a 1-SORA drug (T/F)
T/F
pKa
- pKa of the sedative hypnotic barbiturates is 7.4-8.5
- In the acidic urine (pH 6) environment of the kidney tubule >90% is unionized and so it is extensively REABSORBED
log P
- logP of the sedative-hypnotic barbiturates is 1.5-2
- As lipophilicity increases, so generally does the plasma protein binding
- High protein binding means poor kidney filtration
Flurazepam & Triazolam are promoted as sleep-inducing agents, what is the pharmacokinetic parameter that argues for their use in insomnia?
short tmax (rapid onset)
Between Flurazepam & Triazolam which one causes significant sleep hangover?
Why?
- Flurazepam
- can cause significant sleep hangover due to accumulation of its LONG LIVED active metabolite
- Triazolam’s active metabolite has a short t1/2 due to rapid glucoronidation
Induction of P450’s UGTs and Gama-ALA sunthetase all contribute to barbiturate drug interactions (T/F)
True
In order to possess appreciable sedative-hypnotic activity a barbituric acid derivative must have a logP of 2-3 (T/F)
False
Eszopiclone is a good choice of hypnotic agent to treat problems with sleep maintenance (T/F)
True
Esicarbezapine is a pro-drug for oxcarbazepine (T/F)
False