Drug interactions detected by a computer-assisted prescription system in primary care patients in Spain: MULTIPAP study

Figures & data

Table 1. Clinically relevant drug–drug interactions, types, effects, and frequencies.

Number of relevant DDIs (type D and/ or X) per patient		Number of patients (n = 297)	(%^a)
1		137	23.1
2		59	9.9
3–4		78	13.2
≥ 5		23	3.9
Patients with at least 1 type D DDI Top 10 most frequent type D interactions	Effect	n = 279	47
Combination of drugs with CNS depressant effects (non-opioids)	Risk of CNS depressant effect	64	10.8
Benzodiazepines/opioids	Risk of deep sedation and respiratory depression	35	5.9
Amlodipine/Simvastatin	Risk of increased levels of simvastatin	31	5.2
Combination of high- and low-risk drugs for QT interval prolongation	Risk of QT segment prolongation	21	3.5
Duplication of benzodiazepines	Risk of sedation, falls and confusion	20	3.4
ACEI/ Allopurinol	Risk of skin reactions	16	2.7
Citalopram, escitalopram and cilostazol/CYP2C19 Inhibitors	Risk of QT segment prolongation	15	2.5
Triple whammy (ACEI or AIIRA/ diuretic/ NSAID)	Risk of renal failure	15	2.5
Insulins/ SGLT2 inhibitors	Risk of acidosis	14	2.3
Sulfonylureas/ DPP-IV Inhibitors	Risk of severe hypoglycaemia	13	2.2

^aPercentage of the total number of patients studied (n = 593). DDI: drug–drug interaction; Type D: consider therapy modification; Type X: avoid combination; CNS: central nervous system; ACEI: angiotensin-converting enzyme inhibitor; AIIRA: angiotensin II receptor antagonist; PPI: proton pump inhibitor; NSAID: non-steroidal anti-inflammatory drug.

Table 2. Clinically relevant drug–disease interactions, types, effects, and frequencies.

Number of relevant DdIs per patient		Number of patients (n = 142)	(%^a)
1		100	16.9
2		32	5.4
3-4		10	1.7
Patients with at least 1 type D DdI Top 10 most frequent type D interactions	Effect
Use of long-acting β2 agonists in severe asthma	May worsen asthma	31	5.2
Interactions of various drugs that affect renal failure	Possibility of decreasing GF or renal toxicity	29	4.9
Use of benzodiazepines in COPD	Increased risk of respiratory depression	25	4.2
Use of beta-blockers in peripheral arterial disease	May worsen peripheral vascular disease	20	3.4
Use of COX-2 inhibitors in patients with high cardiovascular risk	Increases the risk of thrombotic events	8	1.3
Use of β2-agonists in patients with heart disease	May worsen heart function	6	1
Use of drugs that prolong the QT interval in patients with heart disease	Increased risk of prolonged QT interval in patients with heart disease	6	1
Use of benzodiazepines without antidepressants in anxiety/depression	Increased risk of increased self-injurious ideation	5	0.8
Use of vitamin D analogues in renal failure	May reduce the effectiveness of vitamin D analogues	5	0.8
Use of vitamin K analogues/various situations	Protein binding of the drug may be reduced	4	0.7

^aPercentage of the total number of patients studied (n = 593). DdI: drug–disease interaction; Type D: consider therapy modification COPD: chronic obstructive pulmonary disease; GF: glomerular filtration.

Table 3. Factors associated with the presence of clinically relevant drug–drug interactions (type D and/or X) adjusted for age and sex.

	OR	95% CI	p
Number of drugs
5–6 drugs	Reference
7–9 drugs	2.83	1.89–4.25	<0.001
≥10 drugs	11.86	6.92–20.33	<0.001
Anxiety/depression	1.98	1.31–2.98	<0.001
Arterial hypertension	0.62	0.41–0.94	0.02
Diabetes	0.57	0.40–0.82	0.003
Ischaemic heart disease	0.43	0.25–0.74	0.002

Pseudo-R²: 0.1353; Akaike’s information criterion: 728.87; Bayesian information criterion: 768.34.

Type D interaction: consider therapy modification; Type X interaction: avoid combination.