Preparing for Oseltamivir Shortage

The influenza season, it appears, is coming on strong this year, and our intensive care unit seems to be reflecting that: I think about 15% of the patients in the ICU have influenza A. Although not all of the admissions to the unit were secondary to influenza disease, we have had to utilize IV zanamivir in 2 cases already this season for severe influenza disease.

Fortunately, most cases can be treated as an outpatient with either ostelamivir or inhaled zanamivir. The inhaled zanamivir is indicated for children > 7 year of age and probably won’t be too effective for patients with pneumonia due to influenza since drug deposition into the airways is needed for efficacy. (Although this makes me wonder how often inhaled zanamivir is used since most patients have pulmonary manifestations of influenza…) Thus oral oseltamivir is widely used to treat influenza.

The one question that comes up is whether or not there is the potential for drug shortage of osteltamivir during the influenza season. Currently, the FDA and ASHP do not report any shortage of oseltamivir at the moment. Although they don’t report any issues as of yet, it appears that our distributor had limited quantities for allocation – especially the liquid formation of oseltamivir – which in turn means that there is a potential for drug shortage in the near future.

Pharmacies should be increasing their inventories to meet the demand for influenza treatment. Determining which pharmacies have a good supply of oseltamivir could be helpful as you can send your patients to a place that will carry the medication (also, you should check which ones are willing to compound medication if needed). However, finding the pediatric liquid formulation may be difficult in some areas, and there are other options to be able to provide oseltamivir to children.

For infants, the liquid suspension should be used, since weight based dosing is preferred when available (3 mg/kg/dose PO q12h for 5 days). The liquid formulation is available at a 6 mg/mL strength. The bottle size is 60 mL and pharmacies may consider dispensing only the required volume to optimize their inventory (although somewhere in the back of my head, this seems like repackaging).

If in case there is a shortage of commercially available oseltamivir, an extemporaneous preparation can be made from the capsules in emergency situations (the recipe is available in drug information sources such as Lexicomp). Being familiar with pharmacies that are willing to compound the medication may come in handy if there is a shortage of oseltamivir suspension.

For children, capsules can be opened and mixed with sweetened liquid – considering that Lexicomp provides example such as chocolate syrup, brown sugar dissolved in water, you can probably mix it with a number of different things. Osteltamivir comes in 30 mg, 45 mg, and 75 mg capsules and the recommended dosing for children is:

Weight	Dose	Capsule Size per Dose
≤ 15 kg	30 mg PO q12h for 5 days	One 30 mg capsule
> 15 – 23 kg	45 mg PO q12h for 5 days	One 45 mg capsule
> 23 – 40 kg	60 mg PO q12h for 5 days	Two 30 mg capsule
> 40 kg	75 mg PO q12h for 5 days	One 75 mg capsule