ANSWER # 1 PHARMACOLOGY. Methadone answers Stoltzfus 4/5/2012 METHADONE: WHY GRANDMA S TAKING A DIPHENYLHEPTANE (ANSWERS) JANUARY 26, 2017

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1 METHADONE: WHY GRANDMA S TAKING A DIPHENYLHEPTANE (ANSWERS) JANUARY 26, 2017 Ky Stoltzfus, MD Assistant Professor, Internal Medicine University of Kansas Medical Center ANSWER # 1 Your response might be that it acts on the mu opioid receptors and: 1. Kappa receptors 2. Neurokinin receptors 3. NMDA receptors 4. GABA receptors PHARMACOLOGY Acts on mu and NMDA receptors 80-90% oral bioavailability Lipophilic No active metabolites and biotransformation to an active drug is not required Half life: hours Duration of analgesia: 6-12 hours 1

2 ANSWER #2 You astutely respond, It s not a good idea to use it in patients: 1. With renal failure 2. With liver failure 3. Older than 65 years old 4. Who have a prior history of drug abuse PHARMACOLOGY Metabolized primary by liver with fecal excretion Metabolized by cytochrome P450 3A4 Important because of drug-drug interactions. QUESTION # 3 CONTINUED He developed some dysphagia and was noted by the home nurse to have white plaques in his oropharynx and you prescribed fluconazole about 3 days ago for candida esophagitis. His wife started cooking with a lot of turmeric recently because she heard it is a natural anti-cancer drug. Upon visiting him today you note that he s become very lethargic and has a slightly slowed respiratory rate at about 8-10 breaths/minute. His wife reports that he s been more lethargic over the past few days. 2

3 ANSWER #3 You think it may be one his medications causing this, what would you consider first: 1. Buproprion 2. Timolol 3. Fluconazole 4. Turmeric DRUG INTERACTIONS Agents That May INCREASE Serum Methadone Concentrations Antidepressants: SSRIs, amitriptyline Antifungals: fluconazole, ketoconazole, posaconazole ANSWER # 4 You decide to discontinue: 1. Metoprolol 2. Risperdone 3. Ceftriaxone 4. Hydrocortisone ointment 3

4 MORE DRUG INTERACTIONS Agents That May DECREASE Serum Methadone Concentrations Antiepileptics: carbamazepine, phenobarbital, phenytoin Antipsychotics: risperidone Antiretrovirals: nevirapine, ritonavir Antitubercular: rifampin Other: St. John s Wort CONTRAINDICATED Cisapride (Propulsid) Quinidine Dronedarone (Multaq) MAOIs Phenothiazines: chlorpromazine (Thorazine), procholpromazine (Compazine), promethazine (Phenergan) Ziprasidone (Geodon) THE BOTTOM LINE Be alert and aware of patients on Methadone and: Cardiac meds Antiretrovirals Psych meds Nausea meds 4

5 SAFETY High caution in patients with liver dysfunction. No dose adjustment for patients with renal failure. However, two prospective studies on methadone excluded patients with kidney and liver disease. 1,2 Patients older than 65 years old have decreased clearance of methadone Ripamonti C, Switching from morphine to oral methadone. 2. Mercadante S, Switching from morphine to methadone. 3. Plummer JL, Estimation of methadone clearance. ANSWER # 5 You reply: 1. Above 300 ms 2. Above 440 ms 3. Above 500 ms 4. Oh, I didn t know we should check an EKG. RECOMMENDATIONS FOR SAFELY STARTING Disclosure: inform patient of arrhythmia risk Clinical History: screen history of structural heart disease, arrhythmia, & syncope Screening: EKG, baseline QTc, 30 day, annually. Additional EKGs if using >100mg/day or unexplained syncope or seizures. 5

6 RECOMMENDATIONS FOR SAFELY STARTING (CONTINUED) Risk Stratification: If QTc is ms: discuss risk/benefit, closer monitoring If >500 ms: consider discontinuing or reducing avoid hypokalemia consider alternative therapy Drug Interaction: be aware of methadonedrug interactions Dose reduce by 50% for patients older than 65yo STARTING METHADONE Opioid naïve: Counsel patient Check EKG Look for drug-drug interactions Start 1 2.5mg PO/PR every 8 hours Titrate every 5-7 days ALTERNATIVE STARTING DOSE (NAÏVE PATIENT) Begin fixed dose methadone 5 or 10 mg orally bid or tid for 4-7 days. If incomplete pain relief, increase the dose by 50% and continue for 4-7 days. Continue increasing dose every 4-7 days until stable pain relief achieved. Breakthrough pain: use an alternative short acting oral opioid with short half-life (e.g. morphine 10 mg) every 1 h PRN for breakthrough pain and to provide pain relief during titration phase. This dose too may need to be titrated based on efficacy. Von Gunten C, Fast Fact # 86 6

7 ONE MORE ALTERNATIVE (NAÏVE PATIENT) Load: Start methadone at fixed oral dose (e.g. 5 or 10 mg) q 4h PRN only. Calculate Maintenance: On day 8, calculate the total methadone dosage taken over the last 24 hour period and give that in scheduled, divided doses bid or tid. Give 10% of total daily methadone as PRN drug q1h for breakthrough pain. Instruct the patient to call you if they need to use more than 5 breakthrough doses per day. Example: if someone took a total of 45 mg methadone on day 7 they would be converted to 15 mg tid scheduled with 5 mg as the prn dose. Von Gunten C, Fast Fact # 86 OPIOID TOLERANT PATIENTS (AKA THIS AINT MY FIRST RODEO) Stop & Go approach Stop all opioids then start Methadone Reduce & Replace Reduce by 30% each day over 3 days REDUCE AND REPLACE Day 1 Decrease previous opioid usage by 1/3 Replace with 3% of previous daily oral morphine equivalent dosage, given as PO/PR every 8 hours Day 2 Decrease previous opioid usage by 1/3 if pain is controlled with rescue short-acting opioid Increase Methadone dosage only if pain is moderate to severe Day 3 Discontinue final 1/3 of previous opioid For breakthrough pain, give rescue dose of ~10% daily methadone dose PO/PR Continue daily assessment of pain and dose titration until effective stable dose of methadone reached Bruera E. Role of Methadone. 7

8 HOW TO CONVERT First, be aware it s complex and use reference materials Second, check your work Third, double check your work Fourth, consider asking a colleague to double check your work A physician, ARNP, pharmacist ANSWER # 6 MS Contin 300mg MS IR 180mg Total 480mg 1 st day: 320mg oral morphine (66% of previous) 15mg Methadone 5mg TID (3% of OME) Target dose: ~45mg Methadone 15mg TID (over 3 days) ANSWER # 7 Hydromorphone basal: 72mg in 24hrs (3mg x 24) demand: 24mg in 24hrs (1mg x 24) TOTAL: 96mg in 24hrs Convert to OME: x / 96 = 30 / 1.5 x = 1920mg OME (30 : 1.5 conversion IV Dilaudid to PO Morphine) First day: change basal to 2mg/hr (33% reduction), keep demand same, start Methadone 50-60mg per day (3% of OME) Target: ~96mg Methadone per day (using 1:20 ratio) 8

9 REVIEW Methadone has good opioid and neuropathic pain activity Keep safety in mind When starting or converting to methadone: Discuss risks/benefits with the patient Look for potential interactions Check and double check your math 9