Summary Information

Classification Chemicals / Complex Chemical Agents / Type:

(This chemicals section is currently predominantly used in Wildpro to link different data types and demonstrate inter-relationships. It does not contain detailed information on the chemical itself.)

Alternative Names --
Notes Information in this page has been entered to support the current volumes of Wildpro and further information will be added as new volumes are completed. This page is not intended to substitute for the manufacturer's data sheet and the information is not yet complete for all species, or for all contra-indications etc.

CAUTION: Before any pharmaceutical product is used, the manufacturer's data sheet, containing information on uses, dosage and administration, contra-indications, warnings etc., should always be consulted. It is important to remember that licensing of pharmaceutical products for use in a particular species/condition, as well as mandatory meat and milk withdrawal times for food-producing animals, varies between countries and changes with time. Withdrawal times also may vary between different pharmaceutical formulations and depending on route of administration. In the EU, the prescription cascade must be followed (see LCofC1.2H and W564.Apr05.w1); note that specific restrictions apply for food-producing animals. In the USA, FARAD may be consulted regarding residues and meat and milk withdrawal times.

  • Famciclovir is given orally and converted in vivo to penciclovir. It is active against HSV-1, HSV-2 and VZV. (J549.30.w1)
  • Famciclovir is the diacetyl-6-deoxy analogue of penciclovir. It has good absorption following oral administration (77% availability). (J222.340.w1)
  • Diacetyl ester of 6-deoxypenciclovir. (B560.14.w14)
  • It is metabolised in the gastro-intestinal tract, blood and liver by deacetylation to penciclovir and is then oxidised in the liver at position 6 on the purine ring. (J222.340.w1)
  • Plasma half-life is two hours. (J222.340.w1)
  • The intracellular half-life of pencyclovir triphosphate, the active form, is 7 - 20 hours. (J222.340.w1)
  • Active against genital herpes and VZV. (J222.340.w1)
  • For further information see: Penciclovir
  • Adverse effects in humans include:
    • Headache, nausea and diarrhoea as uncommon effects which are probably direct; the dose may need to be reduced. (J222.340.w1)
    • Theoretically famciclovir may interact with other drugs which inhibit or need oxidation in the liver. (J222.340.w1)


  • Famciclovir, given rectally at 8.0 - 15.0 mg/kg in Elephas maximus - Asian Elephant provides concentrations of the active metabolite penciclovir at concentrations which, in humans, are considered therapeutic. (J375.1.w1, P503.1.w4)
  • In healthy young Elephas maximus - Asian Elephant, oral dosing with 5 mg/kg famciclovir gave plasma penciclovir values Cmax 1.3 g/mL at Tmax 1.1 hr; rectal dosing with 5 mg/kg famciclovir gave plasma penciclovir values Cmax 1.2 g/mL at Tmax 0.66 hr . Rectal dosing with 15 mg/kg famciclovir gave plasma penciclovir values Cmax 3.6 g/mL at Tmax 1.1 hr and t1/2 was 2.6 hr. Famciclovir was rapidly biotransformed to the active penciclovir and was not detectable in plasma. (P503.1.w4)

The following information is taken with permission directly from the Elephant Care International website (W580.Sept2005.w7):

Famciclovir is a human anti-viral drug that has been used to treat endotheliotrophic herpesvirus (EEHV) infection in Asian elephants.



Note: Herpesvirus infections in elephants are acute, severe and often fatal. To date only 3 of the known cases have survived. Two of these were treated with famciclovir rectally and one was treated orally. At least 3 elephants treated with famciclovir have not survived. In the surviving elephants, loading doses varied from 10.6 to 16.6 mg/kg and duration of treatment varied from 15 to 26 days. Dosages were adjusted during treatment and other supportive drugs were included in the treatment regimen. Veterinarians are urged to contact experienced colleagues for the latest treatment recommendations in suspected cases.


A study to determine the pharmacokinetic parameters is currently under way. Preliminary results suggest 5 mg/kg orally will result in drug levels that should be therapeutic in elephants (Ramiro Isaza, Kansas State University, personal communication).


Elephant References (Only those references that include treatment information are listed below. For a complete list of elephant herpesvirus references see our Database - Herpesvirus [within the Elephant Care International website])

a) Montali,R.J., Richman,L.K., Mikota,S.K., Schmitt,D.L., Larsen,R.S., Hildebrandt,T.B., Isaza,R., and Lindsay,W.A. 2001. Management Aspects of Herpesvirus Infections and Tuberculosis in Elephants. A Research Update on Elephants and Rhinos; Proceedings of the International Elephant and Rhino Research Symposium, Vienna, June 7-11, 2001. Pages: 87-95 Abstract: Elephant endotheliotropic herpesvirus (EEHV) infections and tuberculosis have emerged as causes of illness and mortality in captive elephants. Twenty-six confirmed EEHV cases are documented. Since 1995, 7 have occurred in North America, 10 in Europe and 2 in Asia. A PCR test was used to detect the virus in symptomatic animals; a serological test to identify carrier elephants is under development. The African elephant is a potential source of the EEHV that is lethal for Asian elephants. Fatal infections have also occurred in Asian elephants without African elephant contacts. Three of 6 elephants recovered after treatment with antiviral famciclovir; however, more research is needed to improve the usefulness of this drug. Asian elephants that are less than 10-years old and have been moved to another facility and/or have had contact with African elephants are at increased risk for contracting EEHV. Animals traveling between facilities with a history of EEHV cases may be at greater risk. All young elephants should be monitored daily for anorexia, lethargy, body swellings and blue discoloration (bruising) of the tongue, and be trained for blood sampling and potential oral and rectal treatment with famciclovir.

b) Schaftenaar,W., Mensink,J.M.C.H., Deboer,A.M., Hildebrandt,T.B., and Fickel,J. 2001. Successful treatment of a sub adult Asian elephant bull (Elephas maximus) infected with elephant herpes virus. Proc. of the International Symposium for Diseases of Zoo and Wildlife Animals (Rotterdam).

c) Schmitt,D.L., Hardy,D.A., Montali,R.J., Richman,L.K., Lindsay,W.A., Isaza,R., and West,G. 2000. Use of famciclovir for the treatment of endotheliotrophic herpesvirus infections in Asian elephants (Elephas maximus). Journal of Zoo and Wildlife Medicine 31:(4):518-522 
Abstract: Two juvenile Asian elephants (E. maximus) presented with an acute onset of facial oedema and lethargy. Examination of the oral cavity of each animal revealed cyanosis of the tip and distal margins of the tongue suggestive of endothelial inclusion body disease (EIBD) of elephants. Whole-blood samples were obtained, and polymerase chain reaction tests confirmed the presence of elephant herpesvirus. The animals were administered famciclovir (Flamvir; 500 mg/70 kg body weight, with a loading dose of 1000 mg/70 kg body weight) a potent human anti-herpesvirus drug, in the course of their disease, and recovery followed a treatment regime of 3-4 wk. These are the first known cases of elephants surviving EIBD.

d) Schmitt,D.L., Hardy,D.A. 1998. Use of famciclovir for the treatment of herpesvirus in an Asian elephant. Journal of the Elephant Managers' Association 9:103-104 

Great Apes

  • Primates: for the treatment of herpesvirus infections. (D425.3.15.w3o)
    • 3-4 mg/kg orally three times daily for seven days.
    •  5-6 mg/kg orally twice daily for seven days.
    • 10-12 mg/kg orally once daily for seven days.

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