Status: no longer manufactured; phased out

Organizations involved:

Lilly, Eli & Co. – Manuf.; R&D; Tech.; World mark.

Cross ref: See the Insulin Products entry (#559).

Description: Insulin, Pork, Purified (Lente Iletin II - Pork) is insulin derived from porcine (pig) pancreas tissue in aqueous formulations for subcutaneous injection.  The pork insulin is available in a range of insulin formulations, e.g., NPH and Lente.  Pork insulin (C256H381N65O76S6) is composed of 21-amino acid chain A linked via cysteine at residue 7 to cysteine at residue 7 of 22-amino acid chain B.  It has a molecular weight of 5777.66 Daltons (about 5.8 kDa). 

Iletin II products contain insulin at a concentration of 100 Units/mL (U-100).  Lente Iletin II contains an amorphous, crystalline suspension of pork insulin (Iletin II) complexed with zinc.  NPH Iletin II contains pork insulin in a standard NPH formulation.  Iletin II products are stored at 2-8˚C (refrigerated), but may be kept at up to 30˚C (86˚F) if needed. 

Nomenclature: Insulin, Pork/Lilly [BIO]; Iletin II [TR for uncomplexed or regular formulation]; Lente Iletin II [TR; Lente is reg. to Novo Nordisk]; Regular Iletin II [TR]; NPH Iletin II [TR for NPH formulation]; Insulin Zinc Suspension, Purified Pork [FDA for Lente formulation]; Insulin Zinc [CAS USAN BAN JAN for Lente formulation]; Insulin Zinc Suspension, Compound [INN for Lente formulation]; Insulin Zinc Purified Porcine (Suspension) [JAN for Lente formulation]; Iletin I [TR former, for beef insulin]; 12584-58-6 [CAS for regular insulin, including pork]; 9004-14-2 [CAS RN for insulin, regular unbuffered/neutral]; 8049-62-5 [CAS RN]; 12584-58-6 [CAS RN for insulin pork Lente]; NDC 00002-8411-01; NDC 00002-8311-01; NDC 00002-8211-01 [NDC]

Note, Chemical Abstracts Service (CAS) names and numbers do not distinguish between insulins based on their source, just their basic structures.  Iletin was Lilly’s original brand name for insulin when it was introduced in the 1920s.

Companies: Iletin II products were manufactured and marketed in the U.S. and internationally by Eli Lilly.

FDA class: Drug NDA OTC

Approvals: Date = in 1920s; introduction of Lilly pork-derived insulin (Ilitin)

Date = 19660617; NDA (017931) for Iletin I

Date = 19791205; NDA (018344) for Ilitin II (presumably, manufactured using then-new purification methods)

Date= 20020211; NDA supplement; Indication = addition of warning about “This insulin being discontinued” to product insert/labeling

Indications: for treatment of diabetes [unofficial]; As over-the-counter (OTC) drugs, these products do not have the usual health care professional product inserts/labeling

Status: In July 2005, Lilly announced it is discontinuing Iletin II and NPH Iletin II due to a drop in sales and use by diabetics.  Existing supplies were expected to run out around the end of 2005.  With this, there will be no pork insulin products approved in the U.S.

These products had been available and approved as over-the-counter (OTC; no prescription required) drugs. 

Tech. transfer: There are no unexpired patents for these products reported in the FDA Orange Book Database. 

Market: The 2005 Average Wholesale Price (AWP) is not available (not in 2005 Red Book).  The 2004 AWP for Iletin II Regular Pork, Iletin II Lente Pork, and Iletin II NPH Pork was $47.98/U-100 (100 U/mL), 10 mL vial (Red Book, 2004).

In July 2005, when Lilly announced discontinuation of Iletin insulins, only ~2,000 patients were purchasing the products, and Lilly presumed many of these were using it for veterinary applications (diabetic dogs and cats).