Theophylline(continued)
▶Valacicloviris predicted to increase the exposure to
theophylline.rTheoretical
Thiazide diuretics→seeTABLE 18p. 851 (hyponatraemia),TABLE 8
p. 848 (hypotension),TABLE 17p. 851 (reduced serum potassium)bendroflumethiazide.chlortalidone.clopamide.cyclopenthiazide.
hydrochlorothiazide.hydroflumethiazide.indapamide.
metolazone.xipamide..
▶Thiazide diureticsare predicted to increase the risk of
hypersensitivity reactions when given withallopurinol.r
Theoretical
▶Aspirin(high-dose) increases the risk of acute renal failure
when given withthiazide diuretics.rTheoretical
▶Thiazide diureticsincrease the risk of hypercalcaemia when
given withcalcium salts.rAnecdotal
▶Thiazide diureticsincrease the concentration oflithium. Avoid
or adjust dose and monitor concentration.rStudy
▶NSAIDsincrease the risk of acute renal failure when given with
thiazide diuretics.rTheoretical→Also seeTABLE 18p. 851
▶Reboxetineis predicted to increase the risk of hypokalaemia
when given withthiazide diuretics.oAnecdotal
▶Thiazide diureticsare predicted to increase the risk of
hypercalcaemia when given withtoremifene.rTheoretical
▶Thiazide diureticsincrease the risk of hypercalcaemia when
given withvitamin D substances.oTheoretical
Thiopental→seeTABLE 8p. 848 (hypotension),TABLE 11p. 849 (CNS
depressant effects)
▶Sulfonamidesare predicted to increase the effects of
thiopental.oTheoretical
▶Tricyclic antidepressantsincrease the risk of cardiac
arrhythmias and hypotension when given withthiopental.
oStudy→Also seeTABLE 8p. 848
Thiotepa→see alkylating agents
Thyroid hormoneslevothyroxine.liothyronine..
▶Antacidsare predicted to decrease the absorption of
levothyroxine. Separate administration by at least 4 hours.
oAnecdotal
▶Antiarrhythmics(amiodarone)are predicted to increase the risk
of thyroid dysfunction when given withthyroid hormones.
Avoid.oStudy
▶Antiepileptics(carbamazepine, fosphenytoin, phenytoin)are
predicted to increase the risk of hypothyroidism when given
withthyroid hormones.oStudy
▶Antiepileptics(phenobarbital, primidone)are predicted to
decrease the effects ofthyroid hormones.oTheoretical
▶Oralcalcium saltsare predicted to decrease the absorption of
levothyroxine. Separate administration by at least 4 hours.
oAnecdotal
▶Thyroid hormonesare predicted to affect the concentration of
digoxin. Monitor and adjust dose.oTheoretical
▶Oralhormone replacement therapyis predicted to decrease the
effects ofthyroid hormones.oTheoretical
▶Iron (oral)decreases the absorption oflevothyroxine. Separate
administration by at least 4 hours.oStudy
▶Lanthanumdecreases the absorption ofthyroid hormones.
Separate administration by 2 hours.oStudy
▶Polystyrene sulfonateis predicted to decrease the absorption
oflevothyroxine. Separate administration by at least 4 hours.
oTheoretical
▶Sucralfatedecreases the absorption oflevothyroxine. Separate
administration by at least 4 hours.oStudy
Tiagabine→see antiepileptics
Tiaprofenic acid→see NSAIDs
Tibolone→seeTABLE 5p. 847 (thromboembolism)
Ticagrelor→seeTABLE 4p. 847 (antiplatelet effects)
▶Antiarrhythmics(amiodarone)are predicted to increase the
exposure toticagrelor. Use with caution or avoid.rStudy
▶Antiepileptics(carbamazepine, fosphenytoin, phenobarbital,
phenytoin, primidone)are predicted to markedly decrease the
exposure toticagrelor. Avoid.rStudy
▶Antifungals, azoles(itraconazole, ketoconazole, voriconazole)are
predicted to markedly increase the exposure toticagrelor.
Avoid.rStudy▶Bosentanis predicted to decrease the exposure toticagrelor.
oTheoretical
▶Ciclosporinis predicted to increase the exposure toticagrelor.
Use with caution or avoid.rStudy
▶Cobicistatis predicted to markedly increase the exposure to
ticagrelor. Avoid.rStudy
▶Ticagrelorincreases the concentration ofdigoxin.o
Study
▶Efavirenzis predicted to decrease the exposure toticagrelor.
oTheoretical
▶Enzalutamideis predicted to markedly decrease the exposure
toticagrelor. Avoid.rStudy
▶Ticagreloris predicted to increase the exposure toergotamine.
Avoid.rTheoretical
▶Grapefruit juicemoderately increases the exposure to
ticagrelor.oStudy
▶HIV-protease inhibitorsare predicted to markedly increase the
exposure toticagrelor. Avoid.rStudy
▶Idelalisibis predicted to markedly increase the exposure to
ticagrelor. Avoid.rStudy
▶Ticagreloris predicted to increase the exposure tolomitapide.
Separate administration by 12 hours.oTheoretical
▶Macrolides(azithromycin)are predicted to increase the
exposure toticagrelor. Use with caution or avoid.rStudy
▶Macrolides(clarithromycin)are predicted to markedly increase
the exposure toticagrelor. Avoid.rStudy
▶Mitotaneis predicted to markedly decrease the exposure to
ticagrelor. Avoid.rStudy
▶Nevirapineis predicted to decrease the exposure toticagrelor.
oTheoretical
▶Ranolazineis predicted to increase the exposure toticagrelor.
Use with caution or avoid.rStudy
▶Rifampicinis predicted to markedly decrease the exposure to
ticagrelor. Avoid.rStudy
▶St John’s Wortis predicted to decrease the exposure to
ticagrelor.oTheoretical
▶Ticagrelorslightly increases the exposure tostatins
(simvastatin). Adjustsimvastatindose,p. 134.oStudy
▶Vemurafenibis predicted to increase the exposure to
ticagrelor. Use with caution or avoid.rStudy
Ticarcillin→see penicillins
Tigecycline→see tetracyclines
Timolol→see beta blockers, non-selective
Tinidazole
▶Alcohol (beverage)potentially causes a disulfiram-like
reaction when given withtinidazole. Avoid for 72 hours
stopping treatment.oTheoretical
▶Tinidazoleis predicted to increase the anticoagulant effect of
coumarins. Monitor INR and adjust dose.rTheoretical
Tinzaparin→see low molecular-weight heparins
Tioguanine→seeTABLE 15p. 850 (myelosuppression)
▶Live vaccinesare predicted to increase the risk of generalised
infection (possibly life-threatening) when given with
tioguanine. Public Health England advises avoid (refer to
Green Book).rTheoretical
Tiotropium→seeTABLE 10p. 849 (antimuscarinics)
Tipranavir→see HIV-protease inhibitors
Tirofiban→seeTABLE 4p. 847 (antiplatelet effects)
Tivozanib
▶Antiepileptics(carbamazepine, fosphenytoin, phenobarbital,
phenytoin, primidone)are predicted to decrease the exposure
totivozanib.rStudy
▶Enzalutamideis predicted to decrease the exposure to
tivozanib.rStudy
▶Mitotaneis predicted to decrease the exposure totivozanib.
rStudy
▶Rifampicinis predicted to decrease the exposure totivozanib.
rStudy
▶St John’s Wortis predicted to decrease the exposure to
tivozanib. Avoid.rStudy
▶Tivozanibis predicted to decrease the exposure tostatins
(rosuvastatin).oTheoretical
Tizanidine→seeTABLE 6p. 848 (bradycardia),TABLE 8p. 848
(hypotension),TABLE 9p. 849 (QT-interval prolongation),TABLE 11p. 849
(CNS depressant effects)1002 Theophylline—Tizanidine BNFC 2018 – 2019
Interactions|Appendix 1A1