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,...

With the deployment of hundreds of thousands of troops in Saudi Arabia, health problems endemic to the Arabian Peninsula may be coming to the attention of physicians in the USA and other areas.

Rapid exposure to altitudes more than 8,000 feet above sea level can cause serious medical problems. Since the last Medical Letter article on this subject (Vol. 30, page 89, 1988), some new information on prevention and treatment of these disorders has been reported.

Sodium hyaluronate (Hyalgan - Sanofi) and hylan G-F 20 (Synvisc - Wyeth- Ayerst) have been approved by the FDA for intra-articular injections in patients with knee pain due to osteoarthritis. Hylan G-F 20 is a cross-linked derivative of hyaluronic acid with a higher molecular weight than sodium hyaluronate. 'Hyaluronan' refers to either the acid or its salt.

The guanylate cyclase-C receptor agonist linaclotide (Linzess – Abbvie/Ironwood) was first approved by the FDA in 2012 for treatment of chronic idiopathic constipation and irritable bowel syndrome with constipation in adults. The drug has now been approved for treatment of functional constipation in patients 6-17 years old. Linaclotide is the only drug to be approved in the US for treatment of functional constipation.

An automatic, noninvasive, glucose-monitoring device (GlucoWatch Biographer) has been approved for marketing by the FDA. The manufacturer states that it is not meant to replace a regular blood glucose meter.

The FDA has approved lubiprostone (Amitiza - Sucampo/Takeda), a chloride channel activator, for treatment of chronic idiopathic constipation in adults. The only other prescription drug approved by the FDA for this indication (in 2004 for adults <= 65 years old) is tegaserod (Zelnorm), a partial agonist of serotonin that is also approved for constipation-predominant irritable bowel syndrome in women. Of course, numerous over-the-counter products are available for treatment of constipation.

The FDA has approved a sublingual tablet (Nocdurna – Ferring) and a nasal spray (Noctiva – Avadel) formulation of desmopressin acetate for treatment of nocturia due to nocturnal polyuria in adults who wake up ≥2 times per night to void. Nocdurna and Noctiva are the first two products to be approved in the US for this indication. Higher-strength nasal spray and oral tablet formulations of desmopressin (DDAVP, and others) have been available for years for treatment of diabetes insipidus and primary nocturnal enuresis (bedwetting in children). In 2007, the indication for primary...

The FDA has approved use of lubiprostone (Amitiza) for treatment of opioid-induced constipation in adults with chronic non-cancer pain. The drug was previously approved for chronic idiopathic constipation and irritable bowel syndrome with constipation.

An intraveneous (IV) formulation of ibuprofen (Caldolor - Cumberland) was recently approved by the FDA for use in adults. It can be administered alone for treatment of mild to moderate pain or as an adjunct to opioid analgesics for moderate to severe pain. It is also approved for reduction of fever.