Abstract
Photodegradation of phenobarbital in aqueous solutions exposed to short-wave ultraviolet light was studied in presence and in absence of sodium thiosulfate. The degradation process appeared to follow first-order kinetics and was found to be dependent on pH, buffer system and sodium thiosulfate concentration. Ionic strength did not have any appreciable effect. The rate of photodegradation was found to be inversely proportional to phenobarbital concentration, especially below 8 × 10−4 M. Solutions of phenobarbital containing alcohol, propylene glycol and benzyl alcohol as cosolvents showed markedly improved stability under UV irradiation in absence of sodium thiosulfate. Complex formation between the thiosulfate anion and phenobarbital appeared to be primarily responsible for the photostabilization of the drug. The equilibrium constant for this complex was calculated to be 36.23 M−1.
- Received October 19, 1993.
- Accepted February 1, 1994.
- Copyright © Parenteral Drug Association. All rights reserved.
PDA members receive access to all articles published in the current year and previous volume year. Institutional subscribers received access to all content. Log in below to receive access to this article if you are either of these.
If you are neither or you are a PDA member trying to access an article outside of your membership license, then you must purchase access to this article (below). If you do not have a username or password for JPST, you will be required to create an account prior to purchasing.
Full issue PDFs are for PDA members only.
Note to pda.org users
The PDA and PDA bookstore websites (www.pda.org and www.pda.org/bookstore) are separate websites from the PDA JPST website. When you first join PDA, your initial UserID and Password are sent to HighWirePress to create your PDA JPST account. Subsequent UserrID and Password changes required at the PDA websites will not pass on to PDA JPST and vice versa. If you forget your PDA JPST UserID and/or Password, you can request help to retrieve UserID and reset Password below.