Metoprolol dosing

In healthy subjects, a single dose of atenolol 100 mg or metoprolol 100 mg did not affect the AUC of a single dose of phenprocoumon, although phenprocoumon levels were slightly higher at 4 and 6 hours after the metoprolol dose. Nevertheless, neither beta blocker altered the prothrombin time response. ... 

The absorption of metoprolol after po dosing is rapid and complete. The dmg undergoes extensive first-pass metabolism in the liver and only 50% of the po dose in bioavailable. About 12% of the plasma concentration is bound to albumin. The elimination half-life is 3—7 h and less than 5% of the po dose is excreted unchanged in the urine. The excretion of the dmg does not appear to be altered in patients having renal disease (98,99,108). 

P-Blockersa Inhibit AV nodal conduction by slowing AV nodal conduction and prolonging AV nodal refractoriness Esmolol 500 mcg/kg IV over 1 minute Propranolol 0.15 mg/kg IV Metoprolol 2.5-5 mg IV x 2-3 doses Esmolol 50-200 mcg/kg/minute continuous infusion Propranolol 80-240 mg/day Metoprolol 50-200 mg/day ... 

Metoprolol 5 mg by slow (over 1 to 2 minutes) IV bolus, repeated every 5 minutes for a total initial dose of 15 mg. If a conservative regimen is desired, initial doses can be reduced to 1 to 2 mg. This is followed in 15 to 30 minutes by 25 to 50 mg orally every 6 hours. If appropriate, initial IV therapy may be omitted. 

Metoprolol CR/XL, carvedilol, and bisoprolol are the only /J-blockers shown to reduce mortality in large HF trials. It cannot be assumed that immediate-release metoprolol will provide benefits equivalent to metoprolol CR/XL. Because bisoprolol is not available in the necessary starting dose of 1.25 mg, the choice is typically limited to either carvedilol or metoprolol CR/XL. On the basis of regimens proven in large clinical trials to reduce mortality, initial and target oral doses are as follows ... 

Metoprolol succinate CR/XL, 12.5 to 25 mg once daily initially target dose, 200 mg once daily. 

Atenolol, betaxolol, bisoprolol, and metoprolol are cardioselective at low doses and bind more avidly to /Ij-receptors than to /J2-receptors. As a result, they are less likely to provoke bronchospasm and vasoconstriction and may be safer than nonselective /1-blockers in patients with asthma, chronic obstructive pulmonary disease, diabetes, and PAD. Cardioselectiv-ity is a dose-dependent phenomenon, and the effect is lost at higher doses. 

Blocker therapy is appropriate to further modify disease in LV dysfunction and is a component of this first-line regimen (standard therapy) for these patients. Because of the risk of exacerbating heart failure, they must be started in very low doses and titrated slowly to high doses based on tolerability. Bisoprolol, carvedilol, and metoprolol succinate are the only /j-blockers proven to be beneficial in LV dysfunction. 

Compounds that exhibit roughly the same affinity to and j32 rsceptors independent of dosage such as nadolol, propranolol, pindolol, timolol, and labetalol (combined a- and j3-adrenoblocker) are classified as nonselective blockers. Drugs which in therapeutic doses have higher affinity to -receptors than to j32-receptors such as acebutol, atenolol, metoprolol, and esmolol, are called selective or cardioselective j3-adrenoblockers. 

Unlike propranolol, which blocks both and j32-adrenoreceptors, metoprolol exhibits cardioselective action, i.e in therapeutic doses, it blocks -adrenoreceptors with insignificant reaction on j32-adrenoreceptors. 

Tablets, extended release - The extended-release tablets are for once daily administration. When switching from immediate-release metoprolol tablets to extended-release, use the same daily dose.

Because of their relative - selectivity, low doses of metoprolol, acebutolol, bisoprolol, and atenolol may be used with caution in patients with bronchospastic disease who do not respond to, or cannot tolerate, other antihypertensive treatment. Bradycardia Metoprolol produces a decrease in sinus heart rate in most patients this decrease is greatest among patients with high initial heart rates and least among patients with low initial heart rates. 

Ciprofloxacin (Cipro, Cipro XR, Proquin XR) [Antibiotic/ Fluoroquinolone] Uses Rx lower resp tract, sinuses, skin skin structure, bone/joints, urinary tract Infxns including prostatitis Action Quinolone antibiotic DNA gyrase Dose Adults. 250-750 mg PO ql2h XR 500-1000 mg PO q24h or 200-400 mg IV ql2h in renal impair Caution [C, /-] Children <18 y Contra Component sensitivity Disp Tabs, susp, inj SE Restlessness, N/V/D, rash, ruptured tendons, T LFTs Interactions T Effects Wf probenecid T effects OF diazepam, theophylline, caffeine, metoprolol, propranolol, phenytoin, warfarin effects W/ antacids, didanosine, Fe salts. Mg, sucralfate, Na bicarbonate,... 

Flurazepam (Dalmane) [C-IV] [Sedative/Hypnotic/ Benzodiazepine] Uses Insomnia Action Benzodiazepine Dose Adults Beds >15 y. 15-30 mg PO qhs PRN X in elderly Caution [X, /-] Elderly, low albumin, hepatic impair Contra NAG PRG Disp Caps SE Hangover d/t accumulation of metabolites, apnea, anaphylaxis, angioedema, amnesia Interactions T CNS depression W/ antidepressants, antihistamines, opioids, EtOH T effects OF digoxin, phenytoin T effects W/ cimetidine, disulfiram, fluoxetine, iso-niazid, ketoconazole, metoprolol, OCPs, propranolol, SSRIs, valproic acid. 

Methimazole (Tapazole) [Antithyroid Agent] Uses Hyperthy-roidism, thyrotoxicosis, pr for thyroid surgery or radiation Action Blocks T3 T4 formation Dose Adults. Initial 15-60 mg/d PO tid Maint 5-15 mg PO daily Peds. Initial 0.4-0.7 mg/kg/24 h PO tid Maint V h- U h of initial dose PO daily w/ food Caution [D, +/-] Contra Breast-feeding Disp Tabs SE GI upset, dizziness, blood dyscrasias Interactions t Effects OF digitalis glycosides, metoprolol, propranolol X effects OF anticoagulants, theophylline X effects W/ amiodarone EMS None OD May cause N/V, HA, abd pain, fever, and pale skin symptomatic and supportive... 

Propranolol reduces the frequency and intensity of migraine headache. Other 13-receptor antagonists with preventive efficacy include metoprolol and probably also atenolol, timolol, and nadolol. The mechanism is not known. Since sympathetic activity may enhance skeletal muscle tremor, it is not surprising that 13 antagonists have been found to reduce certain tremors (see Chapter 28). The somatic manifestations of anxiety may respond dramatically to low doses of propranolol, particularly when taken prophylactically. For example, benefit has been found in musicians with performance anxiety ("stage fright"). Propranolol may contribute to the symptomatic treatment of alcohol withdrawal in some patients. 

Atenolol is not extensively metabolized and is excreted primarily in the urine with a half-life of 6 hours it is usually dosed once daily. Recent studies have found atenolol less effective than metoprolol in preventing the complications of hypertension. A possible reason for this difference is that once-daily dosing does not maintain adequate blood levels of atenolol. The usual dosage is 50-100 mg/d. Patients with reduced renal function should receive lower doses. 

Trials of 3-blocker therapy in patients with heart failure are based on the hypothesis that excessive tachycardia and adverse effects of high catecholamine levels on the heart contribute to the downward course of heart failure patients. The results clearly indicate that such therapy is beneficial if initiated very cautiously at low doses, even though acutely blocking the supportive effects of catecholamines can worsen heart failure. Several months of therapy may be required before improvement is noted this usually consists of a slight rise in ejection fraction, slower heart rate, and reduction in symptoms. As noted above, not all 3 blockers have proved useful, but bisoprolol, carvedilol, and metoprolol have been shown to reduce mortality. Trials are underway with the newer 13 blocker, nebivolol. 

---