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Tramadol - Administration Guide

Mechanism of Action

1. Weak mu (μ)-opioid receptor agonism - its active metabolite O-desmethyltramadol (M1) is 2-4x more potent at the opioid receptor than the parent drug
2. Reuptake inhibition of serotonin and norepinephrine - this accounts for a significant portion of its analgesic effect, as it is only partially reversed by naloxone

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Routes of Administration & Doses

Oral (PO) - Most Common Route

• Maximum daily dose: 400 mg/day (some sources cite up to 300 mg/day)
• Bioavailability is 68% after a single oral dose
• Onset of analgesia: within 1 hour of oral dosing
• Peak effect: 2-3 hours after oral dose
• Duration of action: ~6 hours

Intravenous (IV) / Intramuscular (IM)

• Tramadol can be given intravenously (perioperatively and for post-thoracotomy pain)
• Used as an adjunct to regional anesthesia (e.g., added to lidocaine for IV regional anesthesia, added to bupivacaine for intra-articular use after knee arthroscopy)

Other Routes

• Intra-articular: 100 mg mixed with 0.25% bupivacaine for arthroscopic knee surgery - provides prolonged analgesia vs. either drug alone
• Regional nerve blocks: Added to mepivacaine for brachial plexus block to enhance duration of analgesia in a dose-dependent manner

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Special Populations

• Renal/hepatic impairment: The elimination half-life is 6 hours for tramadol and 7.5 hours for its active metabolite. Dose adjustment is required in severe impairment due to reduced clearance.
• Elderly: Use with caution; start at lower doses.
• Children: The FDA restricts use of tramadol in children and recommends against use in breastfeeding women due to risk of serious adverse effects. - Miller's Anesthesia, 10e
• CYP2D6 variability: Because tramadol is metabolized by CYP2D6, poor metabolizers get less analgesia; ultra-rapid metabolizers risk toxicity from high M1 levels.

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Important Drug Interactions & Contraindications

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Adverse Effects

• Common (especially initial period): Nausea, vomiting, dizziness, vertigo, sedation, dry mouth, constipation, sweating
• Serious: Serotonin syndrome, seizures (naloxone does NOT prevent tramadol-induced seizures), respiratory depression (less than classic opioids), angioedema
• Overdose (>500 mg): Coma, hypertension, respiratory depression, apnea; also associated with hypoglycemia
• Less gastrointestinal motility effects and less respiratory depression than traditional opioids

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Key Clinical Points

• Tramadol is not the drug of choice for moderate-to-severe post-surgical pain as a sole agent - the dose needed to relieve pain in 80% of patients (ED80) is ~260 mg, much larger than the usual 50-100 mg dose. - Miller's Anesthesia, 10e
• Physical dependence and withdrawal have been reported with chronic use
• For acute/chronic pain without significant anti-inflammatory needs, it is a useful "middle-ground" between NSAIDs and stronger opioids
• An extended-release preparation is available for around-the-clock dosing in chronic pain

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Rules of Giving Tramadol

Rule 1 - Know the Indication

• Use for mild to moderate pain - it is as effective as morphine for mild-to-moderate pain
• For severe or chronic pain, tramadol is less effective than morphine - do not rely on it as sole therapy
• It does NOT have significant anti-inflammatory effects, so it is not a substitute for NSAIDs in inflammatory conditions
• Goodman & Gilman's Pharmacological Basis of Therapeutics

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Rule 2 - Correct Dose and Frequency

• The drug has a therapeutic ceiling - at increasing doses, nausea and vomiting become limiting factors - Rosen's Emergency Medicine
• Tramadol should be titrated up slowly ("start low, go slow") to minimise side effects during the initial treatment period

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Rule 3 - Know Who NOT to Give It To (Absolute Rules)

Hard Contraindications

Use With Great Caution

• Patients on SSRIs, SNRIs, TCAs, triptans, St. John's Wort, dextromethorphan - high risk of serotonin syndrome and seizures
• Patients with a history of addiction - tramadol should NOT be considered a non-addictive alternative to opioids; abuse is well-documented - Rosen's Emergency Medicine
• Severe renal/hepatic impairment - reduces clearance of tramadol and its active metabolite (M1, half-life 9 hours)

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Rule 4 - Beware the Serotonin Syndrome Rule

• SSRIs (fluoxetine, sertraline, paroxetine)
• SNRIs (venlafaxine, duloxetine)
• TCAs (amitriptyline, clomipramine)
• MAO inhibitors
• Triptans (sumatriptan)
• Antipsychotics
• Dextromethorphan (in cold/cough medicines)
• St. John's Wort

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Rule 5 - CYP2D6 Interaction Rule

• CYP2D6 inhibitors (paroxetine, fluoxetine, bupropion) - reduce conversion to M1, reducing analgesia
• CYP2D6 ultra-rapid metabolisers (UMs) - overproduce M1, leading to toxicity risk
• CPIC (Clinical Pharmacogenomics Implementation Consortium) guidelines recommend against tramadol use in CYP2D6 ultra-rapid metabolisers - Lippincott Illustrated Reviews: Pharmacology

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Rule 6 - Naloxone Does NOT Fully Reverse Tramadol

• Unlike pure opioids, naloxone only partially reverses tramadol toxicity
• Naloxone administration in tramadol overdose has been associated with an increased risk of seizures
• Tramadol-induced seizures are usually single and self-limiting; anticonvulsants are typically not required - Lippincott Illustrated Reviews: Pharmacology; Tintinalli's Emergency Medicine

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Rule 7 - Taper Before Stopping

• Tramadol causes physical dependence with chronic use
• Do not stop abruptly - taper the dose to prevent withdrawal symptoms - Goodman & Gilman's

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Rule 8 - Prescribe in Pure Form

• Tramadol should be prescribed in pure form to allow accurate dosage adjustments, unless using a fixed combination (tramadol 37.5 mg + acetaminophen 325 mg, which has similar efficacy to hydrocodone 5 mg + acetaminophen 325 mg) - Rosen's Emergency Medicine

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Quick Summary Mnemonic

• S - Seizure history = avoid
• T - Taper on discontinuation
• A - Addiction risk - not a "safe" opioid
• R - Renal/hepatic dose reduction
• T - Titrate slowly (start low)
• S - Serotonergic drugs = contraindicated
• A - Age (children = avoid; elderly = reduce dose)
• F - Full reversal by naloxone is NOT possible
• E - Elderly = max 300 mg/day

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How to Give Tramadol + Safe & Unsafe Combinations

How to Give Tramadol (Step-by-Step)

Step 1 - Choose the Right Route

Step 2 - Start Low, Titrate Up

• Adults: Start at 50 mg every 6 hours
• Titrate up to 100 mg every 4-6 hours based on response
• Never start at maximum dose - initial side effects (nausea, dizziness) are dose-dependent
• Elderly: Begin at 25-50 mg once or twice daily; increase slowly

Step 3 - Duration

• Immediate-release: acts within 1 hour, peaks at 2-3 hours, lasts ~6 hours
• Extended-release: once daily dosing for sustained coverage

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Combinations - The Good (Safe & Beneficial)

1. Tramadol + Paracetamol/Acetaminophen (APAP) ✅

• Fixed combination: Tramadol 37.5 mg + Paracetamol 325 mg (e.g., Ultracet)
• Has similar efficacy to hydrocodone 5 mg + paracetamol 325 mg
• Synergistic effect - different mechanisms act at different pain pathway points
• Reduces the tramadol dose needed, thus reducing side effects - Rosen's Emergency Medicine

2. Tramadol + NSAIDs (Ibuprofen, Diclofenac, Ketorolac) ✅

• Part of multimodal analgesia - each drug targets a different part of the pain pathway
• NSAIDs reduce peripheral inflammation; tramadol acts centrally
• This combination is opioid-sparing - reduces total opioid consumption and side effects
• Commonly used in the perioperative setting - Miller's Anesthesia, 10e

3. Tramadol + Low-dose Ketamine ✅

• Small-dose ketamine (NMDA receptor antagonist) is a useful addition to perioperative tramadol in abdominal surgery
• Enhances post-op analgesia beyond what tramadol alone provides - Miller's Anesthesia, 10e

4. Tramadol + Local Anaesthetics (for Regional/Intra-articular Use) ✅

• Intra-articular: Tramadol 100 mg + 0.25% bupivacaine - significantly prolongs post-arthroscopy analgesia vs. either alone
• Brachial plexus block: Added to 1.5% mepivacaine - enhances duration in a dose-dependent manner
• IV regional anaesthesia (Bier's block): Added to lidocaine - shorter onset of sensory block - Miller's Anesthesia, 10e

5. Tramadol + Gabapentinoids (Gabapentin/Pregabalin) ✅

• Gabapentin and pregabalin are adjuvant analgesics used in multimodal regimens
• Useful for neuropathic pain components; complementary mechanism (calcium channel modulation)
• Reduces opioid requirements in the perioperative period

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Combinations - The Dangerous (Never or Avoid) ❌

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Tramadol's Place in the WHO Analgesic Ladder

Step 3 - Strong opioids (morphine, oxycodone) ← severe pain
Step 2 - Weak opioids (TRAMADOL, codeine) ← mild-to-moderate pain
Step 1 - NSAIDs + Paracetamol ← mild pain

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Practical Summary Table

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