Sildenafil
Contraindicated
Textbook-cited
Precipitous and potentially fatal fall in blood pressure; myocardial ischemia.
Concurrent use is absolutely contraindicated
Source: KDT 7e · p950
Drug reference
Isosorbide dinitrate
Nitrate · Antianginal
NitrateAntianginal
CDSCO approved
EXCRETION
—
not curated
INTERACTIONS
8 major
incl. contraindicated
PREGNANCY
—
not curated
Top interactionssee all 8 →
- SildenafilContraindicatedTextbook-citedKDT 7e · p950
- TadalafilContraindicatedTextbook-citedKDT 7e · p950
- AvanafilSevereDatabaseDDInter
- Nitrous AcidSevereDatabaseDDInter
Mechanism
Isosorbide dinitrate is an organic nitrate that must be metabolized (reduced) to produce gaseous nitric oxide (NO). NO then activates guanylyl cyclase, increasing the cellular level of cyclic GMP. This leads to the activation of protein kinase G and modulation of phosphodiesterases. In smooth muscle, the net result is reduced phosphorylation of myosin light chain, causing vasodilation.
Indications
Ischaemic pain (e.g., in unstable angina, NSTEMI, acute coronary syndromes)Heart failurecombination with hydralazine provides survival benefit in chronic heart failure
Dosing
- Adult
- intravenous for ischaemic pain if sublingual glyceryl trinitrate is ineffective
Pharmacokinetics
Bioavailability
PO: 22 ± 14%; SL: 45 ± 16%; PC: 33 ± 17%
Protein binding
28 ± 12%
Metabolism
Metabolized (reduced) to produce nitric oxide (NO).
Excretion
<1%
Drug interactions
Tadalafil
Contraindicated
Textbook-cited
Precipitous and potentially fatal fall in blood pressure; myocardial ischemia
Concurrent use is absolutely contraindicated
Source: KDT 7e · p950
Avanafil
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Nitrous Acid
Severe
Database
Clinical effect not specified
Source: DDInter
Prilocaine
Severe
Database
Clinical effect not specified
Source: DDInter
Riociguat
Severe
Database
Clinical effect not specified
Source: DDInter
Tizanidine
Severe
Database
.
Source: DDInter
Vardenafil
Severe
Database
Clinical effect not specified
Source: DDInter
4 additional unreviewed or low-confidence interactions hidden because their provenance or source detail is insufficient.
Related guidelines
Other Nitrate drugs
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Textbook-sourced·Sources: KD Tripathi 7e, Goodman & Gilman 14e, Katzung, BNF·Updated: 2026-05-10