lithium toxicity - fmge march 2012

All of the following are part of the treatment of lithium toxicity, except:{fmge march 2012,aipg 2006}
A. Treating dehydration
B. Ingestion of polystyrene sulfonate
C. Hemodialysis
D. Using an antagonist


Correct answer : D. Using an antagonist


There is no known antagonist for lithium



Which of the following antihypertensive drugs is contraindicated in a patient on Lithium in order to prevent toxicity?{aipg 2011)
A. Clonidine
B. Beta blockers
C. Calcium channel blockers
D. Diuretics


ans=D


reason is actually it interferes with the transport of lithium across the tubule. . So Li accumulates. . It is very simple that it causes Na excretion which competes with Li excretion! 


Three major drug classes have been identified as potential precipitants of lithium toxicity:


* Diuretics that promote renal sodium wasting
* Angiotensin-converting enzyme (ACE) inhibitors that reduce glomerular filtration rate (GFR) and enhance the tubular reabsorption of lithium
* Nonsteroidal anti-inflammatory drugs (NSAIDs) that reduce GFR and interrupt of renal prostaglandin synthesis

 
Diuretics acting distally to the proximal tubule, such as thiazides and spironolactone, do not directly affect the fractional excretion of lithium (although they may affect serum lithium levels indirectly through their effects on volume status). Reabsorption of lithium is increased and toxicity is more likely in patients who are hyponatremic or volume depleted, both of which are possible consequences of diuretic therapy.  

we don't know the exact question  but these are the probable questions formats.