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Flashcards in Drug interactions Deck (14):
1

Pharmacokinetic interaction

delivery of object drug to its site of action is altered by precipitant drug

2

Pharmacodynamic interaction

the response of the object drug is modified by the precipitant drug without changes in drug concentrations

3

pharmaceutic interactions

physical and chemical incompatibilities

4

Drugs that SLOW gastric emtying

Opiate anagesics, antimuscarinics (atropine), tricyclic antidepressants (antimuscarinic side effects).

5

In general, what is the effect of an antacid on the absorption of an acidic drug? A basic drug?

Less acidic stomach contents means more acidic drug will be in its ionised form, therefore will be absorbed slower. If the drug is basic, less will be ionized and more absorbed faster. EtOH has opposite effects.

Note: most absorption is in intestine, so absorption in stomach is not super clinically relevant.

6

In general, what is the effect of an antacid on the absorption of an acidic drug? A basic drug?

Less acidic stomach contents means more acidic drug will be in its ionised form, therefore will be absorbed slower. If the drug is basic, less will be ionized and more absorbed faster. EtOH has opposite effects.

Note: most absorption is in intestine, so absorption in stomach is not super clinically relevant.

7

Tetracyclines and polyvalent cations

Tetracyclines chelate cations- effect is greatly reduced availability of tetracycline. Solution: administer min 2hrs apart.

8

Cholestyramine

Basic anion exchange resin will bind to ANY acidic drug that is coadministered.

9

Cholestyramine

Basic anion exchange resin will bind to ANY acidic drug that is coadministered.

10

What are some p450 inducers?

Rifampicin, ethanol, phenytoin

11

What are som p450 inhibitors?

Azoles, grapefruit juice, cimetidine

12

How does induction work and how long does it take?

Via transcriptional upregulation of CYP gene. Requires days-2 weeks to peak. Requires 1+ week to return to baseline. Excdeption is EtOH- faster induction.

13

What are some pharmacodynamic interactions?

NSAIDs-antihypertensives (opposite effectsw on Na and water retention)

14

What are some pharmacodynamic interactions?

NSAIDs-antihypertensives (opposite effectsw on Na and water retention)
Naloxone-opiates
MAOI-SSRI, Linezolid-SSRI- Additive seritonergic effects. fatal
Beta-blocker-theophylline- antagonized bronchodilation of theophylline