Rimantadine
Risk Factor: CM
Class: ANTI-INFECTIVES
/ Antivirals
Contents of this page:
Fetal Risk Summary
Breast Feeding Summary
References
Questions and Answers
Fetal Risk Summary
Rimantadine is a synthetic antiviral agent used in the prophylaxis and treatment of influenza A virus infections. In nonpregnant patients, rimantadine shares the toxic profile of a similar antiviral agent, amantadine, which is also used for influenza A virus infections (see Amantadine) (1). It is not known whether rimantadine crosses the human placenta to the fetus, but the relatively low molecular weight (about 216) probably ensures that transfer occurs.
Rimantadine was embryotoxic (increased fetal resorption) in rats at a dose 11 times the recommended human dose on a body surface area basis (RHD) (2). This dose also produced maternal toxicity. No embryotoxicity was observed in rabbits given up to 5 times the RHD, but a developmental abnormality was observed as evidenced by an increase in the ratio of fetuses with 1213 ribs from the normal litter distribution of 50:50 to 80:20 (2).
No reports describing the use of rimantadine during human pregnancy have been located. In addition, as of late 1996, the FDA had not received any reports of pregnancy exposure to rimantadine (personal communication, F. Rosa, 1996). Although the lack of human data does not allow an assessment of fetal risk, the absence of significant animal teratogenicity may indicate that rimantadine is a safer agent during pregnancy than the closely related drug, amantadine.
Breast Feeding Summary
Rimantadine is concentrated in the milk of lactating rats with milk levels approximately twice those measured in the serum 23 hours after a dose (2). No reports have described the use of rimantadine during human lactation or breast feeding, but passage of the antiviral agent into human milk should be anticipated because of its relatively low molecular weight (about 216). Because of adverse effects noted in nursing rats whose mothers were given rimantadine, the manufacturer recommends the drug not be administered to nursing women (2).
References
- Morris DJ. Adverse effects and drug interactions of clinical importance with antiviral drugs. Drug Safety 1994;10:28191.
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Product information. Flumadine. Forest Pharmaceuticals, 2000.
Questions and Answers
Do drugs that bind with plasma proteins in the blood tend to stay in the body longer than those that don't?, I know that the kidneys filter them out eventually, but because some drugs have a high protein binding rate (i.e. Allegra, Rimantadine, etc.) would it take the kidneys longer to process them than drugs that don't bind with proteins?
Should stay in bloodstream longer since you get an equilibrium between bound and non-bound forms. Kidneys/liver should only affect the non-bound form directly.
This assumes that the binding and non-binding otherwise have equal clearance rates.
