Dr Sharon Rees @reesprescribe
Day 1: A potent long-acting oral thiazide-like diuretic, #metolazone was discovered in the 1970s. Can be used in combination with loop diuretics for acute heart failure where it may potentiate effect & is postulated to help with diuretic resistance. Mostly used short-term, but some require longterm management
Dr Sharon Rees @reesprescribe
Day 2: #metolazone is licensed in adults for oedema of heart failure or kidney disease, as well as hypertension. Licensed in the UK as Xaqua® as 5 mg divisible tablet (care re switching as imports had other strengths/differences in bioavailability). Dose is 2.5 to 5 mg daily a.m.
Dr Sharon Rees @reesprescribe
Day 3: #metolazone has good oral absorption;take same time daily relative to meal;cmax~1.5hrs. High Vd & protein binding. ~ 10% hydroxylated to inactive metabolites/some enterohepatic recycling. Most excreted unchanged in urine/ small % biliary excretion. T½ 8-10hrs. Note that states of oedema can affect bioavailability for #metolazone; monitor for response variability
Dr Sharon Rees @reesprescribe
Day 4: #metolazone inhibits NaCl symporter & thus Na reabsorption. The action is predominantly in distal tubule, increasing urine volume & reducing fluid accumulation. Also, some Na absorption inhibition occurs in proximal tubule. K+excretion may be less affected compared to other diuretics. #metolazone is believed not to induce the reninangiotensin-aldosterone system, which supports overcoming issues with diuretic resistance. Electrolyte monitoring required
Dr Sharon Rees @reesprescribe
Day 5: Adverse drugs effects for #metolazone: constipation, raised uric acid, glycosuria, electrolyte disturbances, hypotension/falls in elderly. Avoid in pregnancy. Has low renal toxicity with efficacy @lower GFRs (<30); can be used in impaired renal function (caution if severe) (NOT exhaustive)
Dr Sharon Rees @reesprescribe
Day 6: Most ‘severe’ drug-drug interactions relate to hypokalaemia e.g aripiprazole, citalopram, or the risk of renal failure e.g NSAIDs. #metolazone can also increase the concentration of lithium. Many DDIs also increase risk of hypotension e.g alcohol, other antihypertensives (NOT exhaustive)
Dr Sharon Rees @reesprescribe
Day 7: Having similar characteristics to the thiazide family of drugs, #metolazone is a quinazoline-sulfonamide; therefore there is a risk of allergic reaction in cases of sulfonamide allergy, albeit a lower risk than for sulfonamide antibiotics
Earn Your CPD Certificate
With the help of Prescribing and Therapeutics Training Ltd and the Journal of Prescribing Practice, you can earn your 1-hour CPD certificate
In addition to the posts, read the BNF 1 monograph on metolazone and the related treatment summary on ‘Diuretics’. Another useful source is the Summary of Product Characteristics for Xaqua®. See links below. Once you have completed this, answer the 10 questions. Submit your answers to reesprescribe@gmail.com. If you answer at least eight out of 10 questions correctly, you will receive your CPD certificate via email.