Alprazolam

Mechanism

The liver breaks down alprazolam mainly through the enzyme CYP3A4, and itraconazole and its main metabolite hydroxy-itraconazole strongly inhibit this enzyme. In a study with alprazolam 0.8 mg, itraconazole raised the alprazolam area under the curve (AUC) 2.8-fold, while peak concentration did not change. More alprazolam stays in the blood, and its sedative effect becomes stronger and may last longer. The inhibition reaches full strength only when itraconazole reaches steady state, after about 15 days with the capsules. After itraconazole is stopped, it takes 7–14 days to leave the blood.

Symptoms

Too much alprazolam shows as drowsiness, slurred speech, poor coordination, confusion, lethargy, low muscle tone and low blood pressure. Severe poisoning can bring respiratory depression and, rarely, coma. The risk is higher if the person also takes alcohol or other drugs that depress the nervous system.

Management

The combination is contraindicated. The alprazolam label forbids use with strong inhibitors of the enzyme CYP3A4 and names itraconazole (alprazolam label, US Food and Drug Administration, FDA). The Spanish alprazolam label does not recommend it with itraconazole or other azole antifungals (alprazolam label, Spanish Agency of Medicines and Medical Devices, AEMPS). The itraconazole documents are milder: they list alprazolam among drugs to use with caution, with close monitoring and a lower dose if needed (itraconazole labels, AEMPS and FDA). After itraconazole is stopped, it takes 7–14 days to leave the blood, and longer in liver cirrhosis. Take this into account when starting alprazolam after a course of itraconazole (itraconazole label, AEMPS). If the two have been taken together, watch for drowsiness, slurred speech, poor coordination, low blood pressure and slowed breathing (alprazolam and itraconazole labels, AEMPS). Alcohol is not recommended with alprazolam because it adds to the sedation (alprazolam label, AEMPS). In a serious overdose, support breathing and circulation. Flumazenil, a benzodiazepine receptor antagonist, may help (alprazolam label, AEMPS).

Mechanism

Ketoconazole strongly inhibits CYP3A4, the enzyme that breaks down alprazolam in the liver. Alprazolam levels rise and its sedative effect is enhanced (FDA labels of both drugs).

Symptoms

Drowsiness, deep sedation, slowed thinking, impaired coordination and speech; in older people, a risk of falls.

Management

The combination is contraindicated: the FDA alprazolam label prohibits use with strong CYP3A4 inhibitors, including ketoconazole, and the FDA ketoconazole label lists alprazolam among contraindicated drugs. The Spanish alprazolam SmPC does not recommend it with ketoconazole and other azole antifungals (alprazolam SmPC). If a patient on alprazolam needs a systemic antifungal, choose one that does not inhibit CYP3A4.

Mechanism

Additive CNS depression, sedation, and anticholinergic effect. In older patients: high delirium and fall risk.

Symptoms

Deep sedation, drowsiness, ataxia, confusion (especially in older patients). Dry mouth, constipation, urinary retention (anticholinergic effect).

Management

Avoid the combination in older patients. If needed, use the minimum effective dose of both with a short course. Alternative anxiolytic when a TCA is needed: hydroxyzine or gabapentinoids.

Mechanism

Carbamazepine induces CYP3A4; alprazolam plasma levels fall by 50%. Loss of anxiolytic effect and withdrawal symptoms (anxiety, insomnia, tremor) are possible.

Symptoms

Return of anxiety, insomnia, tremor, sweating, tachycardia (withdrawal). With high carbamazepine doses, full return of panic disorder symptoms is possible.

Management

During carbamazepine therapy, increase alprazolam by 50% or switch to lorazepam/oxazepam (glucuronidated, no CYP3A4 dependence). Alternative anticonvulsants without induction: levetiracetam, lamotrigine.

Mechanism

Alprazolam depresses the central nervous system, and its label approved by the US Food and Drug Administration (FDA) lists antihistamines among the drugs that add to this effect. At the recommended 10 mg dose, objective tests show no relevant effect of cetirizine on driving ability, but in sensitive patients other CNS depressants can further reduce attention and performance (cetirizine SmPC).

Symptoms

Drowsiness, reduced attention and slower reactions, impaired coordination (cetirizine SmPC; alprazolam SmPC). In older or debilitated patients alprazolam more often causes ataxia and oversedation (alprazolam SmPC).

Management

The alprazolam label approved by the US Food and Drug Administration (FDA) requires limiting the dose and duration of alprazolam used with CNS depressants and lists antihistamines among them. The Spanish alprazolam SmPC sets the same limit for sedating antihistamines (alprazolam SmPC). The patient is warned about drowsiness and told not to drive or operate machinery until it is clear how they tolerate the combination; the cetirizine dose is not exceeded (cetirizine SmPC; alprazolam label, FDA). In older or debilitated patients alprazolam is started at 0.25 mg two or three times daily and kept at the lowest effective dose to avoid ataxia and oversedation (alprazolam SmPC). The US over-the-counter cetirizine label tells people taking tranquilizers or sedatives to ask a doctor or pharmacist before use (cetirizine label, FDA).

Mechanism

Clarithromycin blocks CYP3A4 – the main alprazolam metabolic route. Alprazolam plasma levels rise 2- to 3-fold, with prolonged and stronger effect.

Symptoms

Prolonged sedation, drowsiness, dizziness, ataxia. Falls and fracture risk in older patients. Symptoms appear within 1–2 days.

Management

During clarithromycin therapy, halve the alprazolam dose. Alternative antibiotics: azithromycin or doxycycline (minimal CYP3A4 impact). Alternative benzodiazepines without CYP3A4 dependence: lorazepam, oxazepam.

Mechanism

Dronedarone is a strong CYP3A4 inhibitor, the main alprazolam metabolic route. Alprazolam plasma levels may rise 2- to 4-fold. Deep sedation, fall risk in older patients.

Symptoms

Deep sedation, drowsiness, ataxia. Older patients: fall and fracture risk. Symptoms appear within 1–2 days.

Management

During dronedarone therapy, halve alprazolam or use lorazepam/oxazepam (glucuronidated, no CYP3A4 dependence).

Mechanism

Fluconazole at 200 mg/day or above blocks CYP3A4 – the main alprazolam metabolic route. Alprazolam plasma levels rise 2- to 3-fold, with stronger and longer effect.

Symptoms

Deep sedation, drowsiness, ataxia. Particularly dangerous in older patients – fall and fracture risk. Symptoms appear within 1–2 days.

Management

During fluconazole therapy, halve the alprazolam dose. Alternative antifungals: terbinafine or echinocandins. Alternative benzodiazepines without CYP3A4 dependence: lorazepam or oxazepam.

Mechanism

Fluoxetine slows the elimination of alprazolam. According to the FDA alprazolam label, co-administration raised alprazolam peak concentration by 46%, reduced its clearance by 21%, prolonged its half-life by 17% and worsened psychomotor performance. The FDA fluoxetine label describes the same: alprazolam levels rise and psychomotor function suffers more. The Spanish alprazolam SmPC lists fluoxetine among drugs that need special attention, because inhibitors of liver enzymes, mainly CYP3A4, raise alprazolam levels. Both drugs also act on the central nervous system, and the alprazolam SmPC warns that CNS depression can be enhanced when alprazolam is combined with antidepressants.

Symptoms

Drowsiness, slowed reactions and impaired psychomotor performance, as the FDA labels of both drugs describe for this combination. In older people, sedation and muscle weakness raise the risk of falls, often with serious consequences (alprazolam SmPC). Driving and operating machinery become riskier.

Management

Use the combination with caution and with limits on dose and duration: the alprazolam SmPC requires limiting the dose and duration of alprazolam use with antidepressants and asks for special attention when it is combined with fluoxetine. The FDA fluoxetine label advises considering a lower starting dose of the co-administered drug, slow titration and monitoring of the patient's clinical state. Alprazolam itself is given for as short a time as possible, no longer than 2–4 weeks without reassessment, and older people start at a lower dose (alprazolam SmPC). The long half-life of fluoxetine and its metabolite norfluoxetine has to be taken into account when assessing interactions (fluoxetine SmPC).

Mechanism

Alprazolam is cleared in the liver mainly by CYP3A4, and fluvoxamine inhibits this enzyme (labels of both drugs). The FDA fluvoxamine label describes a study with fluvoxamine 100 mg a day: alprazolam AUC, peak concentration and half-life roughly doubled and its clearance fell by about half. At fluvoxamine 300 mg the effect may be stronger. Both drugs also act on the central nervous system, and the alprazolam SmPC warns that CNS depression can be enhanced when alprazolam is combined with antidepressants.

Symptoms

Drowsiness, slowed reactions, and impaired psychomotor performance and memory, as the FDA fluvoxamine label describes for this combination. In older people, sedation and muscle weakness raise the risk of falls, often with serious consequences (alprazolam SmPC). Driving and operating machinery become riskier. Marked depression of the central nervous system can lead to slowed breathing and coma (alprazolam SmPC).

Management

Avoid the combination where possible: the FDA alprazolam label says so and names fluvoxamine. If it cannot be avoided, start alprazolam at no more than half the usual initial dose and titrate to the lowest effective dose; the fluvoxamine dose does not need changing (FDA fluvoxamine label). The Spanish fluvoxamine SmPC also requires a lower dose of such benzodiazepines during co-treatment, and the alprazolam SmPC requires limiting the dose and duration of alprazolam use with antidepressants. In older people alprazolam is started at a lower dose anyway (alprazolam SmPC). Fluvoxamine is unlikely to change the clearance of benzodiazepines eliminated by glucuronidation, such as lorazepam and oxazepam (FDA fluvoxamine label).

Mechanism

Alprazolam and gabapentin depress the central nervous system (CNS) by different pathways, and their effects add up. The alprazolam SmPC warns that combining it with antiepileptics increases CNS depression and the risk of respiratory depression, coma and death (alprazolam SmPC). The gabapentin SmPC reports cases of respiratory depression, sedation and death when gabapentin was taken with other CNS depressants (gabapentin SmPC).

Symptoms

Drowsiness, dizziness, slowed thinking and reactions, impaired coordination. With marked depression: slow, shallow breathing, confusion and loss of consciousness (alprazolam and gabapentin SmPCs). In older patients, drowsiness and dizziness increase the risk of falls (alprazolam and gabapentin SmPCs).

Management

The alprazolam SmPC requires limiting the dose and duration of co-administration with antiepileptics, which include gabapentin (alprazolam SmPC; alprazolam label of the US Food and Drug Administration, FDA). Use alprazolam at the lowest effective dose for the shortest time, no longer than 2–4 weeks; in older patients, start with 0.25 mg two or three times a day and use caution because of sedation, muscle weakness and the risk of falls (alprazolam SmPC). Watch the patient closely for drowsiness, sedation and respiratory depression, and reduce the dose of gabapentin or of the other CNS depressant accordingly (gabapentin SmPC). The risk of severe respiratory depression is higher in older patients and in those with lung disease, neurological disease or renal impairment (gabapentin SmPC). Advise the patient not to drive or operate machinery while taking alprazolam (alprazolam FDA label).

Mechanism

Both drugs depress the central nervous system (CNS). The alprazolam SmPC warns that with antipsychotics the depressant effect can increase, up to respiratory depression, coma and death, and the haloperidol SmPC says haloperidol can enhance the effect of hypnotics and sedatives. The haloperidol SmPC also lists alprazolam among CYP3A4 inhibitors that may raise haloperidol levels, usually by 20–40% and in some cases by up to 100%. Higher haloperidol levels raise the risk of its adverse effects, including QT prolongation on the electrocardiogram.

Symptoms

Drowsiness, slowed reactions, poor coordination and confusion. Marked central nervous system depression can lead to slowed breathing and coma (alprazolam SmPC). In older people, sedation and muscle weakness raise the risk of falls, often with serious consequences (alprazolam SmPC). Haloperidol can cause a fast heart rate and a drop in blood pressure on standing, and QT prolongation carries a risk of ventricular arrhythmias (haloperidol SmPC).

Management

The combination is not prohibited, but the alprazolam SmPC requires limiting the dose and duration of its use with antipsychotics, and haloperidol is one of them. The US Food and Drug Administration (FDA) alprazolam label likewise requires limiting the alprazolam dose and duration with any central nervous system depressant. Alprazolam is given for as short a time as possible, no longer than 2–4 weeks without reassessment, and older or debilitated patients start at a lower dose. In chronic respiratory insufficiency the alprazolam dose is reduced, and in severe respiratory insufficiency or sleep apnoea syndrome alprazolam is contraindicated (alprazolam SmPC). Before haloperidol is started, a baseline electrocardiogram (ECG) is recorded and potassium and magnesium are corrected. With alprazolam the patient is watched for stronger or longer haloperidol effects and the haloperidol dose is reduced if needed; haloperidol is stopped if the QTc interval exceeds 500 ms (haloperidol SmPC).

Mechanism

Additive CNS depression and sedation. No direct pharmacokinetic interaction – levetiracetam is not CYP-metabolised.

Symptoms

Drowsiness, slowed thinking and reactions, impaired coordination. With marked depression: slow, shallow breathing and confusion, up to coma (alprazolam SmPC). In older patients, sedation and muscle weakness increase the risk of falls (alprazolam SmPC).

Management

The alprazolam SmPC requires limiting the dose and duration of co-administration with antiepileptics, which include levetiracetam (alprazolam SmPC; alprazolam label of the US Food and Drug Administration, FDA). Use alprazolam at the lowest effective dose for the shortest time, no longer than 2–4 weeks; in older patients, start with 0.25 mg two or three times a day and use caution because of sedation, muscle weakness and the risk of falls (alprazolam SmPC). Advise the patient not to drive or operate machinery while taking alprazolam (alprazolam FDA label).

Mechanism

Both drugs depress the central nervous system. Mirtazapine increases the sedative effect of benzodiazepines (mirtazapine SmPC), and together they impair attention and coordination more than either drug alone (mirtazapine label, US Food and Drug Administration, FDA). The alprazolam SmPC warns that combining it with antidepressants deepens CNS depression and raises the risk of respiratory depression, coma and death (alprazolam SmPC).

Symptoms

Drowsiness, dizziness, slowed reactions, impaired attention and coordination (mirtazapine SmPC). In older or debilitated patients alprazolam more often causes ataxia and oversedation (alprazolam SmPC). Marked CNS depression can lead to respiratory depression (alprazolam SmPC).

Management

The combination is avoided where possible: the mirtazapine label approved by the US Food and Drug Administration (FDA) advises against taking it with benzodiazepines and names alprazolam. If both drugs are needed, the dose and duration of combined use are limited (alprazolam SmPC; alprazolam label, FDA). The alprazolam course is kept as short as possible, no longer than 2–4 weeks, and is not extended without reassessment (alprazolam SmPC). In older or debilitated patients alprazolam is started at 0.25 mg two or three times daily and kept at the lowest effective dose to avoid ataxia and oversedation (alprazolam SmPC). The patient is warned not to drive or operate machinery until it is clear how they tolerate the combination (mirtazapine SmPC; alprazolam label, FDA).

Mechanism

Alprazolam and morphine act on different receptors (GABA-A and mu-opioid), but both depress the central nervous system and the respiratory centre, and the effects add up. The labels of both drugs warn that together they can cause profound sedation, respiratory depression, coma and death. The US Food and Drug Administration (FDA) puts this risk in the boxed warning of the alprazolam and morphine labels and cites observational studies: with benzodiazepines, the risk of drug-related death is higher than with opioids alone (FDA labels).

Symptoms

Severe drowsiness, reduced alertness, confusion, slow and shallow breathing, low blood pressure; in severe cases coma and death (alprazolam and morphine labels). The patient and caregivers are taught in advance to recognise these signs (alprazolam and morphine labels).

Management

The combination is not prohibited, but the alprazolam and morphine labels allow it only for patients who have no other treatment options. Both drugs are then given at the lowest effective dose for the shortest possible time, and the patient is closely watched for respiratory depression and sedation (alprazolam and morphine labels). The alprazolam and morphine labels approved by the US Food and Drug Administration (FDA) add: in a patient already on morphine, start alprazolam at a lower dose than usual; when morphine is added to alprazolam, lower the starting dose of morphine. Explain the risk and the signs of respiratory depression to the patient and caregivers, advise against driving until the effect of the combination is known, and if the combination is warranted consider prescribing naloxone, the opioid antidote (FDA labels). Alprazolam is given for no longer than 2–4 weeks, at a lower dose in older or debilitated patients and in chronic respiratory insufficiency, and it is contraindicated in severe respiratory insufficiency and sleep apnoea syndrome (alprazolam SmPC); morphine is also given at a lower dose to older patients and in chronic kidney or liver disease (morphine SmPC).

Mechanism

Alprazolam and pregabalin depress the central nervous system (CNS) by different pathways, and their effects add up. The alprazolam SmPC warns that combining it with antiepileptics increases CNS depression and the risk of respiratory depression, coma and death (alprazolam SmPC). Pregabalin enhances the effect of lorazepam, another benzodiazepine, and post-marketing reports describe respiratory failure, coma and death when pregabalin was taken with CNS depressants (pregabalin SmPC of the European Medicines Agency, EMA).

Symptoms

Drowsiness, dizziness, slowed thinking, impaired coordination. With marked depression: slow, shallow breathing, confusion and loss of consciousness (alprazolam and pregabalin SmPCs). In older patients, drowsiness and dizziness increase the risk of falls (alprazolam and pregabalin SmPCs).

Management

The alprazolam SmPC requires limiting the dose and duration of co-administration with antiepileptics, which include pregabalin (alprazolam SmPC; alprazolam label of the US Food and Drug Administration, FDA). Use alprazolam at the lowest effective dose for the shortest time, no longer than 2–4 weeks; in older patients, start with 0.25 mg two or three times a day and use caution because of sedation, muscle weakness and the risk of falls (alprazolam SmPC). The risk of severe respiratory depression is higher when pregabalin is taken with central nervous system depressants, in older patients and in those with lung disease, neurological disease or renal impairment; these patients may need a pregabalin dose adjustment (pregabalin SmPC of the European Medicines Agency, EMA). Advise the patient not to drive or operate machinery while taking alprazolam (alprazolam FDA label).

Mechanism

Both drugs depress the central nervous system. The alprazolam SmPC warns that with antipsychotics the depressant effect can increase, up to respiratory depression, coma and death. Quetiapine acts mainly on the central nervous system, so its SmPC asks for caution when it is combined with other centrally acting drugs.

Symptoms

Drowsiness, sedation, slowed reactions, poor coordination. Quetiapine can cause a drop in blood pressure on standing with dizziness, mostly at the start of treatment and during dose titration, and together with sedation this raises the risk of falls, above all in older people (quetiapine and alprazolam SmPCs). Marked central nervous system depression can lead to slowed breathing and coma (alprazolam SmPC). Driving and operating machinery become riskier.

Management

The combination is not prohibited, but the alprazolam SmPC requires limiting the dose and duration of its use with antipsychotics, and quetiapine is one of them. The US Food and Drug Administration (FDA) alprazolam label requires the same with any central nervous system depressant, and the quetiapine SmPC asks for caution with other centrally acting drugs. Alprazolam is given for as short a time as possible, no longer than 2–4 weeks without reassessment; older or debilitated patients start at a lower dose, the dose is reduced in chronic respiratory insufficiency, and alprazolam is contraindicated in severe respiratory insufficiency and sleep apnoea syndrome (alprazolam SmPC). Warn the patient about drowsiness and dizziness on standing, especially at the start of quetiapine treatment and during dose titration (quetiapine SmPC).

Mechanism

Ritonavir is the most potent CYP3A4 inhibitor available – the main alprazolam metabolic route. Alprazolam plasma levels rise 4-fold. Marked sedation, ataxia, and respiratory depression risk emerge.

Symptoms

Deep sedation, drowsiness, marked ataxia. Older patients: fall and fracture risk. With high alprazolam doses and high ritonavir doses: respiratory depression risk.

Management

Avoid the combination. Alternative benzodiazepines without CYP3A4 dependence: lorazepam or oxazepam (metabolised by glucuronidation, weakly affected by ritonavir). If alprazolam is needed, reduce the dose 4-fold.

Mechanism

Alprazolam and tramadol depress the central nervous system and respiratory centre. Tramadol additionally lowers the seizure threshold and raises serotonergic activity. Fatal overdoses have been reported.

Symptoms

Drowsiness, sedation, slowed breathing. Seizures may occur (tramadol) and syncope from orthostatic hypotension. Older patients: fall risk.

Management

Avoid the combination. For analgesia on alprazolam, use paracetamol, an NSAID, or morphine/oxycodone (with respiratory depression warning). Alternative anxiolytics: hydroxyzine or gabapentinoids.

Mechanism

Both drugs depress the central nervous system (CNS), and their effects add up. The alprazolam SmPC warns that combining it with antiepileptics increases CNS depression and the risk of respiratory depression, coma and death (alprazolam SmPC). Valproate can also enhance the effect of benzodiazepines (valproic acid SmPC).

Symptoms

Drowsiness, slowed thinking and reactions, impaired coordination. With marked depression: slow, shallow breathing and confusion, up to coma (alprazolam SmPC). In older patients, sedation and muscle weakness increase the risk of falls (alprazolam SmPC).

Management

The alprazolam SmPC requires limiting the dose and duration of co-administration with antiepileptics (alprazolam SmPC; alprazolam label of the US Food and Drug Administration, FDA). Use alprazolam at the lowest effective dose for the shortest time, no longer than 2–4 weeks; in older patients, start with 0.25 mg two or three times a day and use caution because of sedation, muscle weakness and the risk of falls (alprazolam SmPC). Valproate can enhance the effect of benzodiazepines, so monitor the patient clinically and adjust the dose when needed (valproic acid SmPC). Advise the patient not to drive or operate machinery while taking alprazolam (alprazolam FDA label).

Mechanism

Additive bradycardia and hypotension. Alprazolam sedation may mask early symptoms of excessive blood pressure drop.

Symptoms

Lower blood pressure, postural dizziness, fatigue. Older patients: fall risk. With additional antihypertensives: bradycardia (pulse below 60/min).

Management

The combination is acceptable for short alprazolam use with pulse and blood pressure monitoring. In older patients, lorazepam at minimum doses is preferable with fall risk warning.

Mechanism

Bupropion lowers seizure threshold, especially at high doses (above 300 mg/day) or in predisposition. Abrupt alprazolam withdrawal further raises seizure risk via GABAergic rebound.

Symptoms

Tremor, jitters, severe cases: seizures. Symptoms appear with bupropion up-titration or abrupt alprazolam withdrawal. In epilepsy or prior head trauma, risk is maximal.

Management

Avoid in epilepsy and prior head trauma. If unavoidable (nicotine dependence with anxiety), start bupropion at 150 mg in the morning and do not exceed 300 mg/day. Do not stop alprazolam abruptly — taper over 4–8 weeks.

Mechanism

Additive hypotension. Alprazolam sedation may mask early orthostatic symptoms.

Symptoms

Lower blood pressure, postural dizziness, fatigue. Older patients: fall risk.

Management

In older patients, check standing and sitting blood pressure 1–2 weeks after start. Alternative anxiolytic: hydroxyzine or a short lorazepam course.

Mechanism

Additive hypotension and sedation. Carvedilol's α/β-blockade causes fatigue and dizziness on its own; alprazolam adds GABAergic CNS depression.

Symptoms

Sedation, fatigue, slowed reactions, impaired coordination. In older patients: fall and fracture risk. Driving and operating machinery: accident risk. Postural dizziness, syncope, fatigue. Older patients: fall and fracture risk.

Management

On starting the combination, begin alprazolam at the minimum dose (0.25 mg at bedtime). In older patients, cap at 0.5 mg/day. Check standing/sitting BP at one week. With pronounced sedation, consider non-drug options for anxiety (CBT, breathing exercises) or switch to buspirone (no sedation).

Mechanism

Additive CNS depression. Citalopram does not inhibit CYP3A4 — no pharmacokinetic interaction with alprazolam. The effect adds up at GABA and serotonin receptors.

Symptoms

Sedation, fatigue, slowed reactions, impaired coordination. In older patients: fall and fracture risk. Driving and operating machinery: accident risk.

Management

On starting the combination, begin alprazolam at the minimum dose. In older patients, cap citalopram at 20 mg/day (QT risk) and alprazolam at 0.5 mg/day. For long-term anxiety treatment, plan CBT as the core therapy with gradual benzodiazepine taper.

Mechanism

Additive CNS depression and hypotension. Clonidine is a central α2-agonist with sedative effect; alprazolam is a GABAergic sedative.

Symptoms

Sedation, fatigue, slowed reactions, impaired coordination. In older patients: fall and fracture risk. Driving and operating machinery: accident risk. Pronounced morning hypotension and bradycardia possible.

Management

On starting the combination, begin both at minimal doses with time-separated dosing (e.g. clonidine in the morning, alprazolam at bedtime). Avoid the combination in older patients — fall risk. In anxiety disorders with hypertension, alternative: a beta-blocker (metoprolol) plus buspirone.

Mechanism

Alprazolam raises blood digoxin levels, more often in patients over 65 (alprazolam labels in Spain and the US). The digoxin SmPC also lists alprazolam among drugs that increase serum digoxin. The documents do not say how large the rise is or what causes it: the FDA digoxin label places alprazolam in the group where the size of the effect is unclear. Digoxin has a narrow therapeutic index (FDA digoxin label), so even this rise can lead to toxicity.

Symptoms

Signs of digoxin toxicity: loss of appetite, nausea, vomiting, weakness, dizziness and visual changes, including yellow-green colour vision. Cardiac effects are rhythm and conduction disorders: ventricular premature beats, often as bigeminy, atrial tachycardia with block, atrioventricular block up to complete heart block, ventricular tachycardia (digoxin labels). Alprazolam itself causes drowsiness and muscle weakness, with a risk of falls in older people (alprazolam SmPC).

Management

The combination is not prohibited, but it is managed by digoxin levels. The FDA alprazolam label requires measuring serum digoxin before alprazolam is started, then checking digoxin levels and signs of toxicity frequently and lowering the digoxin dose if needed. The FDA digoxin label requires the same approach whenever an interacting drug is started, changed or stopped. The Spanish alprazolam SmPC requires watching for signs of digoxin toxicity, especially in patients over 65. Patients on digoxin have serum electrolytes and creatinine checked periodically (digoxin SmPC). In older people alprazolam is started at a lower dose (alprazolam SmPC).

Mechanism

Diltiazem moderately inhibits CYP3A4; alprazolam is a CYP3A4 substrate. Alprazolam AUC rises by 30–50%, prolonging sedation.

Symptoms

Sedation, fatigue, slowed reactions, impaired coordination. In older patients: fall and fracture risk. Driving and operating machinery: accident risk. Morning sedation is especially pronounced (alprazolam half-life is extended).

Management

On starting the combination, reduce alprazolam by 25–50%. In older patients, start at 0.125 mg at bedtime. Antihypertensive alternatives: amlodipine or a beta-blocker without CYP3A4 effect (metoprolol, bisoprolol). Anxiolytic alternatives: lorazepam or oxazepam (CYP3A4-independent), or buspirone.

Mechanism

Additive CNS depression. Duloxetine weakly inhibits CYP2D6 with no CYP3A4 effect — no pharmacokinetic interaction with alprazolam.

Symptoms

Sedation, fatigue, slowed reactions, impaired coordination. In older patients: fall and fracture risk. Driving and operating machinery: accident risk.

Management

On starting the combination, begin alprazolam at the minimum dose. In anxiety with chronic pain (neuropathy, fibromyalgia), the combination is reasonable, but for long-term therapy assess feasibility of benzodiazepine discontinuation via CBT. Avoid the combination in older patients — fall risk.

Mechanism

Additive hypotension. Alprazolam sedation may mask orthostatic symptoms.

Symptoms

Lower blood pressure, postural dizziness, fatigue. Older patients: fall risk.

Management

In older patients, check standing and sitting blood pressure 1–2 weeks after start. Alternative anxiolytic: hydroxyzine or a short lorazepam course.

Mechanism

Additive sedation. No direct pharmacokinetic interaction – escitalopram does not significantly block CYP3A4.

Symptoms

Additional drowsiness, ataxia in the first 1–2 weeks. Older patients: fall risk.

Management

Widely used in anxious-depressive disorders. Alprazolam is given for a short course (4–6 weeks) with gradual taper after escitalopram's effect stabilises. In older patients: minimum alprazolam dose; monitor cognition.

Mechanism

Additive hypotension and fall risk in older patients. No direct pharmacokinetic interaction.

Symptoms

Lower blood pressure, postural dizziness, fatigue. Older patients: fall risk.

Management

In older patients, check standing and sitting blood pressure 1–2 weeks after starting alprazolam. Alternative anxiolytic: hydroxyzine or a short lorazepam course.

Mechanism

Additive hypotension and fall risk. No direct pharmacokinetic interaction.

Symptoms

Lower blood pressure, postural dizziness, fatigue. Older patients: fall risk.

Management

In older patients, check standing and sitting blood pressure 1–2 weeks after start. Alternative anxiolytic: hydroxyzine or a short lorazepam course.

Mechanism

Additive hypotension and fall risk in older patients. Additional delirium risk with diuretic-induced hypovolaemia.

Symptoms

Lower blood pressure, postural dizziness, fatigue. Older patients: fall risk.

Management

In older patients, check standing and sitting blood pressure 1–2 weeks after start; assess fluid and electrolyte balance. Alternative anxiolytic: hydroxyzine or a short lorazepam course.

Mechanism

Additive hypotension. Alprazolam sedation may mask orthostatic symptoms.

Symptoms

Lower blood pressure, postural dizziness, fatigue. Older patients: fall risk.

Management

In older patients, check standing and sitting blood pressure 1–2 weeks after start. Alternative anxiolytic: hydroxyzine or a short lorazepam course.

Mechanism

Additive bradycardia and sedation. Fall risk in older patients.

Symptoms

Lower blood pressure, postural dizziness, fatigue. Older patients: fall risk.

Management

In older patients, check pulse and blood pressure 1–2 weeks after starting alprazolam. Alternative anxiolytic: hydroxyzine or a short lorazepam course.

Mechanism

Additive hypotension with sublingual nitroglycerin. Alprazolam sedation may worsen dizziness.

Symptoms

Lower blood pressure, postural dizziness, fatigue. Older patients: fall risk.

Management

The patient takes the first nitroglycerin dose sitting or lying down. Warn the patient about fall risk after nitroglycerin while on alprazolam.

Mechanism

Omeprazole weakly blocks CYP3A4; alprazolam plasma levels may rise slightly. The effect is clinically weak.

Symptoms

Minimal changes: mild additional sedation in some patients. Older patients: rare ataxia.

Management

Dose adjustment is usually unnecessary. In older patients and prolonged therapy, monitor cognition and fall risk.

Mechanism

Additive bradycardia, hypotension, and sedation. Propranolol is non-selective (blocks β1 and β2); risk higher than with bisoprolol.

Symptoms

Lower blood pressure, postural dizziness, fatigue. Older patients: fall risk.

Management

In older patients, check pulse and blood pressure 1–2 weeks after start. In asthma or COPD, a selective beta-blocker (bisoprolol, metoprolol) is preferable. Alternative anxiolytic: hydroxyzine or a short lorazepam course.

Mechanism

Tacrolimus is a weak CYP3A4 inhibitor; alprazolam is a CYP3A4 substrate. Alprazolam levels may rise moderately. Additive sedative effect.

Symptoms

Sedation, fatigue, slowed reactions, impaired coordination. In older patients: fall and fracture risk. Driving and operating machinery: accident risk.

Management

On starting the combination, begin alprazolam at 0.25 mg at bedtime. In transplant patients, prefer buspirone or CBT for anxiety over benzodiazepines. If unavoidable, tacrolimus monitoring is unchanged, but check sedation at 1 and 2 weeks after starting alprazolam.

Mechanism

Additive orthostatic hypotension. Tamsulosin (α1-blocker) directly vasodilates; alprazolam mildly lowers BP and amplifies the orthostatic response.

Symptoms

Postural dizziness, syncope, fatigue. Older patients: fall and fracture risk. Sedation, fatigue, slowed reactions, impaired coordination. In older patients: fall and fracture risk. Driving and operating machinery: accident risk.

Management

On starting the combination, take tamsulosin in the evening (to minimise daytime weakness) and alprazolam at bedtime. In older patients, start alprazolam at 0.125 mg. Check standing/sitting BP at 1 and 2 weeks. With pronounced orthostatic hypotension, consider switching tamsulosin to silodosin (minimal BP effect).

Mechanism

Additive hypotension. Benzodiazepines have weak hypotensive effect; the main one comes from the ARB. In most patients, clinically minor.

Symptoms

Postural dizziness, syncope, fatigue. Older patients: fall and fracture risk. Morning weakness possible at standard doses.

Management

No dose adjustment usually needed. In older patients on starting telmisartan, check standing/sitting BP at one week. With pronounced morning hypotension, move alprazolam from night to morning or switch to buspirone.

Mechanism

Additive CNS depression (minimal for venlafaxine, mainly from alprazolam). High-dose venlafaxine (above 150 mg/day) also raises BP.

Symptoms

Sedation, fatigue, slowed reactions, impaired coordination. In older patients: fall and fracture risk. Driving and operating machinery: accident risk.

Management

On starting the combination, begin alprazolam at the minimum dose. For long-term anxiety treatment, prioritise antidepressant monotherapy with CBT and gradual benzodiazepine taper. In arterial hypertension, check BP 2 weeks after starting venlafaxine.

Mechanism

No direct interaction. Mild additive hypotension and fall risk in older patients during hypovolaemia or on starting the combination.

Symptoms

Possible mild morning hypotension and sedation. In older patients: fall risk.

Management

No dose adjustment needed. In older patients, start alprazolam at 0.125 mg at bedtime. In dehydration or acute illness, temporarily stop spironolactone.