Many prescriptions for eye drops call for instillation of 1-2 drops. But Medical Letter consultants in ophthalmology seem to agree that all eye drops should generally be given in doses of only one drop. The volume of a single drop can vary with the viscosity of the solution, the design of the dropper, and patient technique. The average volume of a drop is 35-50 microliters, but can be as high as 75 microliters. An eye brimming with fluid holds 30 microliters at best, so even one drop is often an overdose. A second either washes out the first or increases the possibility of systemic toxicity,...

Carnitine is a naturally occurring amino acid derivative essential for transport of long-chain fatty acids into mitochondria. It is advertised on the Internet as a dietary supplement that can promote weight loss, increase energy, enhance athletic performance and slow aging. Levocarnitine (Carnitor - Sigma-Tau) has been FDA approved for oral and parenteral treatment of primary carnitine deficiency since 1986. Products containing levocarnitine and its synthetic derivative acetyl-L-carnitine are available as dietary supplements in the US.

Betaxolol (Kerlone - Searle), an oral beta-adrenergic blocker, was recently approved by the US Food and Drug Administration for once-daily treatment of hypertension. The new drug is beta 1 (cardio)-selective with no intrinsic sympathomimetic (partial agonist) activity. It is also available in a topical formulation for treatment of glaucoma (Betoptic - Medical Letter, 28:45, 1986). Beta-blockers currently available in the USA for treatment of hypertension are listed in the table below.

Clostridioides (formerly Clostridium) difficile infection (CDI) is the most common infectious cause of healthcare-associated diarrhea in adults. Guidelines on management of CDI have recently been updated.

Duetact (Takeda), a new fixed-dose combination of the thiazolidinedione pioglitazone (Actos) and the sulfonylurea glimepiride (Amaryl, and others), was recently approved by the FDA for treatment of type 2 diabetes. It is approved as an adjunct to diet and exercise to improve glycemic control in patients already taking pioglitazone and/or a sulfonylurea. Avandaryl, a combination of glimepiride and the thiazolidinedione rosiglitazone, was approved in 2006.

The FDA has approved the dipeptidyl peptidase-4 (DPP-4) inhibitor alogliptin (Nesina – Takeda) for treatment of type 2 diabetes. In addition to the single-ingredient product, the FDA also approved fixed-dose combinations of alogliptin/metformin (Kazano) and alogliptin/pioglitazone (Oseni) for the same indication. Alogliptin is the fourth DPP-4 inhibitor to become available in the US. The other three – saxagliptin (Onglyza), sitagliptin (Januvia), and linagliptin (Tradjenta) – are also available in fixed-dose combinations with metformin.

Recently published guidelines from the American Diabetes Association (ADA) and the Kidney Disease: Improving Global Outcomes (KDIGO) Diabetes Work Group recommend addition of the oral nonsteroidal mineralocorticoid receptor antagonist (MRA) finerenone (Kerendia) to standard treatment in patients with type 2 diabetes and chronic kidney disease (CKD).

Mibefradil dihydrochloride (Posicor - Roche), a chemically distinct nondihydropyridine calcium-channel blocker, has been approved by the US Food and Drug Administration (FDA) and is being heavily promoted as the first T-type calcium-channel blocker for treatment of hypertension and chronic stable angina.

Colonoscopy remains the preferred method of colorectal cancer screening. Many patients consider cleansing the bowel in preparation for colonoscopy the most unpleasant part of the procedure, but inadequate bowel preparation significantly lowers the diagnostic yield.

The FDA has approved daprodustat (Jesduvroq – GSK), a hypoxia-inducible factor prolyl hydroxylase inhibitor (HIF-PHI), for oral treatment of anemia due to chronic kidney disease (CKD) in adults who have been on dialysis for at least 4 months. It is the first HIF-PHI and the first oral drug to be approved in the US for this indication.