Drug-Disease Precautions

Conditions where certain medications require caution or are contraindicated.

Overview

Drug-disease interactions (DDSIs) occur when a medication worsens an existing condition or when a disease state affects drug action. These are critical considerations for drug repurposing.

Categories

Absolute Contraindications

Medications that should NOT be used in certain conditions:

Drug Class	Contraindicated Condition	Reason
NSAIDs	Active GI bleeding	Worsens bleeding
Beta-blockers	Severe asthma	Bronchospasm risk
Metformin	Severe renal impairment	Lactic acidosis
ACE inhibitors	Angioedema history	Recurrence risk

Relative Contraindications

Medications requiring careful risk-benefit assessment:

Drug Class	Precaution Condition	Consideration
Anticoagulants	Fall risk	Bleeding risk
Antipsychotics	Dementia	Mortality increase
Corticosteroids	Diabetes	Glucose elevation
Thiazides	Gout	Uric acid increase

Organ-Specific Precautions

Renal Impairment

Drug	Concern	Action
Metformin	Lactic acidosis	Reduce dose or avoid
NSAIDs	Worsening function	Avoid
Aminoglycosides	Nephrotoxicity	Dose adjust

Hepatic Impairment

Drug	Concern	Action
Paracetamol	Hepatotoxicity	Limit dose
Statins	Elevated enzymes	Monitor LFTs
Methotrexate	Hepatic fibrosis	Avoid if severe

Cardiac Conditions

Condition	Drugs to Avoid	Reason
Heart failure	NSAIDs, Thiazolidinediones	Fluid retention
Long QT	QT-prolonging drugs	Arrhythmia
Bradycardia	Beta-blockers, Digoxin	Worsening

Special Populations

Elderly

Consideration	Examples
Anticholinergic burden	Antihistamines, TCAs
Fall risk medications	Benzodiazepines, Antihypertensives
Renal dose adjustment	Most drugs cleared renally

Pregnancy

Category	Drugs to Avoid
Teratogenic	Methotrexate, Warfarin, Retinoids
Third trimester	NSAIDs, ACE inhibitors

Paediatric

Consideration	Examples
Contraindicated	Tetracyclines, Fluoroquinolones
Dose adjustment	Most medications

Evidence Sources

Source	Description
Product labelling	Manufacturer information
Clinical guidelines	Society recommendations
Post-marketing surveillance	Real-world safety data
DrugBank	Comprehensive drug data

Using This Information

For Repurposing Research

When considering a drug for a new indication:

Review all DDSIs for the drug
Consider the target population
Assess if repurposed use changes risk profile
Plan appropriate monitoring

Clinical Relevance

DDSIs may be:

Direct: Drug worsens condition
Indirect: Condition affects drug metabolism
Monitoring-based: Requires closer follow-up

Research Use Only
Drug-disease precaution data is for research purposes. Clinical prescribing decisions must consider individual patient circumstances and current guidelines.