| Drug
Interaction |
| Drug
1 |
Drug
2 |
Nature
of Interaction |
Mechanism
|
|
Acyclovir
|
+ Zidovudine |
Likely overwhelming
fatigue |
Might be due to
additive effect with zidovudine causing bone marrow depression. |
| Amoxycillin
|
Oral
contraceptives (O.C.) |
Failure
of contraceptive effect is likely. |
Not
well understood; however, the oestrogen component of oral contraceptives
undergoes enterohepatic recirculation being repeatedly secreted
in bile as steroid conjugates which then is hydrolysed by gut
bacteria before reabsorption. Antibiotic use is likely to cause
destruction of gut bacteria thereby affecting hydrolysis of
steroid conjugates with resultant poor reabsorption and lower
than normal circulating oestrogen level. |
| Theophylline |
+ Ciprofloxacin
|
Marked rise in
theophylline level with symptoms of theophylline toxicity. |
Quinolones (ciprofloxacin)
seems to inhibit theophylline metabolism by liver delaying its
clearance from the body and increasing its serum level. |
| |
+ Oral contraceptives
(O.C.) |
Raised serum theophylline
level to some extent; no toxicity. |
Oestrogen component
is believed to inhibit metabolism of theophylline by hepatic
microsomal enzymes. |
| |
+ Benzodiazepines
|
Theophylline
may reduce sedative/ anxiolytic effect of benzodiazepines. |
Possibly
due to blockade of adenosine receptors by theophylline. |
| |
+ Erythromycin |
Increase in theophylline serum
level and possible lowering of antibiotic effect. |
Not well understood;
possibly theophylline metabolism is inhibited by the antibiotic
and conversely theophylline affects both absorption and elimination
of erythromycin. |
| Antacids
|
+ ACE
inhibitors |
Bioavailability
of ACE inhibitors (captopril) is reduced by one-third. |
|
