Names and pronunciation
(meth-ill-doe′pa)
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Drug reference
(meth-ill-doe′pa)
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Func. class.: Antihypertensive
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Chem. class.: Centrally acting α-adrenergic inhibitor
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Do not confuse: methyldopa/L-dopa/levodopa
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ACTION: Stimulates central inhibitory α-adrenergic receptors or acts as false transmitter, resulting in reduction of arterial pressure
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USES: Hypertension, hypertensive crisis
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CONTRAINDICATIONS: Active hepatic disease, hypersensitivity, MAOI therapy Precautions: Pregnancy, geriatric patients, cardiac disease, autoimmune disease, depression, dialysis, hemolytic anemia, Parkinson’s disease, pheochromocytoma, sulfite hypersensitivity
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SIDE EFFECTS CNS: Drowsiness, weakness, dizziness, sedation, headache, depression, psy- chosis, paresthesias, parkinsonism, Bell’s palsy, nightmares, drug fever CV: Bradycardia, myocarditis, orthostatic hypotension, angina, edema, weight gain, HF, paradoxic pressor response (IV) EENT: Nasal congestion ENDO: Breast enlargement, gynecomas- tia, amenorrhea GI: Nausea, vomiting, diarrhea, constipa- tion, hepatic dysfunction, sore or “black” tongue, pancreatitis, colitis, flatulence GU: Impotence, failure to ejaculate HEMA: Leukopenia, thrombocytopenia, granulocytopenia, hemolytic anemia, positive Coombs’ test INTEG: Rash, toxic epidermal necrolysis, lupuslike syndrome
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INTERACTIONS • Lithium toxicity: lithium Increase: pressor effect—sympathomi- metic amines, MAOIs; do not use concur- rently with MAOIs Increase: hypotension, CNS toxicity— levodopa Increase: hypotension—diuretics, other antihypertensives Increase: psychosis—haloperidol Increase: CNS depression—alcohol, antihistamines, antidepressants, analge- sics, sedative/hypnotics β- Increase: B/P—phenothiazines, blockers, amphetamines, NSAIDs, tricy- clics, barbiturates Increase: hypoglycemia—TOLBUTamide Decrease: methyldopa absorption—iron Drug/Lab Test Increase: creatinine, LFTs Decrease: platelets, WBC, HB/HcT Interference: urinary uric acid, serum creatinine, AST False increase: urinary catecholamines
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TREATMENT OF OVERDOSE: Gastric evacuation, sympathomimetics may be indicated; if severe, hemodialysis
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DOSAGE AND ROUTES Hypertension/hypertensive crisis • Adult: PO 250-500 mg bid or tid, then adjusted q2days as needed, 0.5-2 g/day in 2-4 divided doses (maintenance), max 3 g/day; IV 250-500 mg in 100 mL D5W q6hr, run over 30-60 min, max 1 g q6hr; switch to oral as soon as possible • Child: PO 10 mg/kg/day in 2-4 divided doses, max 65 mg/kg or 3 g/day, which- ever is less; IV 20-40 mg/kg/day in 4 di- vided doses, max 65 mg/kg or 3 g, whichever is less Renal dose • Adult: PO CCr 10-50 mL/min dose q8- 12hr; CCr <10 mL/min dose q12-24hr
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Available forms: Methyldopa: tabs , 250, 500 mg; methyldopate: 125 inj 50 mg/mL
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Administer: PO route • Increase in dose should be done in the evening to minimize drowsiness • Product should not be withdrawn abruptly Intermittent IV INFUSION route • After diluting with 100 mL D5W; infuse over ½-1 hr M Y-site compatibilities: Alemtuzumab, alfentanil, amikacin, aminophylline, anidulafungin, ascorbic acid, atenolol, atracurium, atropine, aztreonam, benztropine, bivalirudin, bleomycin, bumetanide, buprenorphine, butorpha- nol, calcium chloride/gluconate, caspofungin, cefamandole, ceFAZolin, cefmetazole, cefonicid, cefotaxime, cefoTEtan, cefOXitin, cefTAZidime, ceftizoxime, cefTRIAXone, cefuroxime, cephalothin, chlorproMAZINE, cimeti- dine, clindamycin, cyanocobalamin, cycloSPORINE, DACTINomycin, DAP- TOmycin, dexamethasone, digoxin, dil- tiaZEM, diphenhydrAMINE, DOCEtaxel, DOPamine, doxycycline, enalaprilat, ePHEDrine, EPINEPHrine, epoetin alfa, ertapenem, erythromycin, esmolol, etoposide, etoposide phosphate, famotidine, fenoldopam, fentaNYL, flu- conazole, fludarabine, gatifloxacin, gemcitabine, gentamicin, glycopyrro- late, granisetron, heparin, hydrocorti- sone, HYDROmorphone, hydrOXYzine, IDArubicin, insulin (regular), irinote- can, isoproterenol, labetalol, lido- caine, linezolid, LORazepam, magnesium sulfate, mannitol, mechlor- ethamine, meperidine, metaraminol, methicillin, methoxamine, methyl- PREDNISolone, metoclopramide, metoprolol, metroNIDAZOLE, mezlo- cillin, miconazole, midazolam, milri- none, minocycline, mitoXANTRONE, morphine, moxalactam, multiple vita- mins, mycophenolate mofetil, nafcillin, nalbuphine, naloxone, netilmicin, nitroglycerin, nitroprusside, norepi- nephrine, octreotide, ondansetron, oxacillin, oxaliplatin, oxytocin, PACLi- taxel, palonosetron, pamidronate, pan- curonium, pantoprazole, papaverine, PEMEtrexed, penicillin G potassium/ sodium, pentazocine, phentolamine, phenylephrine, phytonadione, piper- acillin, polymyxin B, potassium chlo- ride, procainamide, prochlorperazine, promethazine, propranolol, prot- amine, pyridoxine, quiNIDine, raNITI- dine, ritodrine, sodium bicarbonate, succinylcholine, SUFentanil, tacroli- mus, teniposide, theophylline, thia- mine, thiotepa, ticarcillin, ticarcillin- clavulanate, tigecycline, tirofiban, tobramycin, tolazoline, trimetaphan, urokinase, vancomycin, vasopressin, vecuronium, verapamil, vinorelbine, voriconazole, zoledronic acid
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Assess: • Blood studies: neutrophils, decreased platelets, CBC • Hemolytic anemia: direct Coombs’ test before, after 6, 12 mo of therapy; a positive test may indicate hemolytic anemia; usually reverses within weeks to months after discontinuing treat- ment; monitor HB/Hct and RBC; do not start therapy in those with hemolytic anemia • Baselines of renal, hepatic studies be- fore therapy begins • Drug-induced hepatitis/drug fever: usually subsides within 3 mo of discon- tinuing therapy • Hypertension: B/P when beginning treatment, periodically thereafter; report significant changes • Allergic reaction: rash, fever, pruritus, urticaria; product should be discontin- ued if antihistamines fail to help • CNS symptoms, especially in geriatric patients; depression, change in mental status • HF: edema, dyspnea, wet crackles, B/P • Renal symptoms: polyuria, oliguria, urinary frequency; I&O ratio, weight; re- port weight gain >5 lb • Product tolerance: may occur within 3 mo of starting treatment; a dosage change and other products may be needed • Beers: avoid in older adults; high risk of CNS effects; may cause bradycardia and orthostatic hypotension • Pregnancy/breastfeeding: use cautiously in pregnancy, breastfeeding; has been used for pregnancy-induced hypertension
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Evaluate: • Therapeutic response: decrease in B/P
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CLINICAL CONSIDERATIONS
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Patient and caregiver information: • To avoid hazardous activities • Not to discontinue product abruptly because withdrawal symptoms may oc- cur: anxiety, increased B/P, headache, insomnia, increased pulse, tremors, nau- sea, sweating • To rise slowly to sitting or standing position to minimize orthostatic hypoten- sion • To notify prescriber of mouth sores, sore throat, fever, swelling of hands or feet, irregular heartbeat, chest pain, signs of angioedema • That excessive perspiration, dehydra- tion, vomiting, diarrhea may lead to fall in B/P; to consult prescriber • That dizziness, fainting, light-head- edness may occur during first few days of therapy • Not to use OTC (cough, cold, allergy) products unless directed by prescriber; that compliance is necessary; not to skip or stop product unless directed by pre- scriber • That product may cause skin rash
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PHARMACOKINETICS PO: Onset 4-6 hr, duration 24-48 hr IV: Onset 4-6 hr, duration 10-16 hr Metabolized by liver, excreted in urine, half-life 2 hr
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• Adult: PO 250-500 mg bid or tid, then adjusted q2days as needed, 0.5-2 g/day in 2-4 divided doses (maintenance), max 3 g/day; IV 250-500 mg in 100 mL D5W q6hr, run over 30-60 min, max 1 g q6hr; switch to oral as soon as possible
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• Adult: PO CCr 10-50 mL/min dose q8- 12hr; CCr <10 mL/min dose q12-24hr
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