Random drugs facts Flashcards
drugs which interfere with folate metabolism
Aminopterin, methotrexate (amethopterin), pyrimethamine, trimethoprim and triamterene act as folate antagonists and produce folate deficiency by inhibiting dihydrofolate reductase.
N2O & sulphonylureas.
Treatment with folic acid antagonists such as methotrexate readily causes megaloblastic anaemia; this can be prevented by therapy with folinic acid (5-formyltetrahydrofolate).
Other drugs such as anticonvulsants, antituberculosis drugs, alcohol and oral contraceptives also reduces the concentration of folate. The mechanism of this effect is uncertain. Possibilities include reduced absorption, prevention of release of folate from tissue stores, altered plasma protein binding, or increased folate metabolism in the liver.
Drugs which can cause decreased lower oesophageal tone
Lower oesophageal tone is decreased by cholinergic inhibition, dopaminergic stimulation, oestrogen, alpha adrenergic inhibition, beta adrenergic stimulation, cholecystokinin, Secretin, Prostaglandin E1.
E.g. Suxamethonium, atropine, glycopyrrolate.
Drugs which rapidly cross BBB include:
Doxapram, physotigmine.
Metobolism of drugs affected by changes in liver blood flow
Vecuronium (& Roc), Lidocaine, fentanyl.
Clearance of drugs is not affected by liver blood flow
Phenytoin, tolbutamide, theophylline, warfarin, barbiturates, benzodiazepines.
Drugs which could precipitate asthma
Neostigmine- anticholinesterases causes bronchocontrictions.
?irritant volatiles- despite being bronchodilators
Therapeutic effect of botulinum toxin
It is an endotoxins produced by Clostridium botulinum (anaerobic). Acts by inhibiting ACh release from nerve terminals.
Use: e.g. detrusor instability in bladder, resistant migraine, cosmetics
How does sodium bicarb work in TCA overdose arrest?
Raises plama pH, which increases protein binding of the drug , and the large sodium load reverses the sodium channel blocking effect.
