The Good, The Bad, and The Ugly

App Store, RxCalc,

When we released RxCalc we did what most companies do, we setup a page for the application and made sure we listed various different contact addresses on the page as well as creating a contacts page. We had hoped we’d get feature requests, support requests, and constructive criticism. What we’ve discovered is our users don’t really provide much feedback. We’ve had some, but not a lot. We have, however, had a few folks give feedback on iTunes. Some great, some not so great. It’s been a strange ride and I thought I’d share some of that feedback here.

The Good

“I’ve been using this app for a week or so, comparing results to a program I’ve used on my Palm for several years. The two calculate very similar results, and I find myself using RxCalc more and more.”

This user actually sent us a direct e-mail with a feature request. He was interested in better options, like being able to enter height in centimeters and being able to adjust the Volume of Distribution value. Just the kind of feedback you hope for, and he asked for something that would make his experience better. Great stuff.

The Bad

“The interface is rigid and clunky…”

Rigid and clunky, ouch. This feedback has actually been quite helpful. We’ve made changes to an upcoming release to address this very problem. We’re hopeful this user will be happy with the change, if he’s still using RxCalc. If he’s not, we hope he gives it another try.

The Ugly

“Does not work. Interface is clunky and gives me error messages when I put in values. I don’t believe for a minute the positive reviews are real. Cannot use product nor would you want to trust calculations (if you can get them from the app!) in a clinical setting. If it smells like garbage, works like garbage, and looks like garbage, it probably is.”

This review just makes us cringe. We know exactly what this user is talking about. The UI in 1.0 is rigid, we thought it was a good thing but it turns out that wasn’t such a great idea. In trying to protect the user we made some mistakes. Those have been addressed in the next release.

For our 1.0 release we focused heavily on the math and tried to keep the UI as simple as possible. Most of the feedback we’ve received has been UI related and we’ve concentrated on those issues. The math has been solid and is something we haven’t taken lightly.

What can you expect?

I think it’s safe to say we’ve addressed these issues in the next release. We hope our users are happy with the changes, and we think you will be.

Relief for Haiti, update

Charity, RxCalc, Special

Aid!Good morning! It looks like yesterday’s Indie+Relief effort was a huge success! Even though we blew it and didn’t get in on the official program we decided to do what we could. We’re sending $50.00 to Doctors without Borders in the name of our users. We’d like to extend our whole hearted thanks to everyone that participated in the various efforts around the Mac Indie scene yesterday.

We’re very small, and the dollar amount we’re sending seems small, but every little bit helps.

THANK YOU!

Relief for Haiti

Charity, RxCalc, Special

The Mac and iPhone Indie community have put together a relief effort for Haiti called Indie+Relief, brought to you by Second Gear Software and Garrett Murray. Apple Core Labs tried to participate but we were just too late due to an overwhelming response, and our lateness to join the effort. Fear not! We’re going to join the effort, just not through Indie Relief.

What does that mean?

Quite simply this. Apple Core Labs will donate all proceeds from sales of RxCalc on January 20, 2010 to Doctors Without Borders to help the people of Haiti.

If you’ve ever considered purchasing RxCalc now would be a great time to give it a try and in the process you’ll help people in need.

Also, while you’re here, take a look at all the great software being offered by Indie Relief, and pick something else up to help fight the good fight!

Thank You.

Evaluation of once-daily gentamicin dosing in children with febrile neutropenia

aminoglycosides, cancer, gentamicin, neutropenia, once-daily dosing, pediatrics, Pharmacokinetics

Once-Daily Gentamicin Dosing in Children with Febrile Neutropenia Resulting from Antineoplastic Therapy

Miriam Inparajah, B.Sc.Phm. | Cecile Wong, B.Sc.Phm. | Cathryn Sibbald, B.Sc.Phm. | Sabrina Boodhan, B.Sc.Phm. | Eshetu G. Atenafu, M.Sc. | Ahmed Naqvi, M.B.B.S., MCPS, MRCP | L. Lee Dupuis, M.Sc.Phm., FCSHP

Pharmacotherapy. 2010 Jan;30(1):43-51

Abstract

Study Objectives. To evaluate an existing once-daily gentamicin dosing guideline in children with febrile neutropenia resulting from antineoplastic therapy and, if necessary, to develop a new simulated dosing guideline that would achieve pharmacokinetic targets more reliably after the first dose.

Design. Pharmacokinetic analysis of data froma retrospective medical record review.

Setting. Hematology-oncology unit of a university-affiliated pediatric hospital in Canada.

Patients. One hundred eleven patients aged 1–18 years who received once-daily gentamicin between April 2006 and January 2008 for the treatment of febrile neutropenia resulting from antineoplastic therapy, and who had plasma gentamicin concentrations determined after their first dose.

Measurements and Main Results. Demographic data, gentamicin dosing information, blood sampling times, and plasma gentamicin concentrations were noted. Plasma gentamicin concentrations were determined at approximately 3 and 6 hours after the start of the 30-minute infusion of the first dose. Pharmacokinetic parameters were calculated according to standard first-order, one-compartment equations. The proportion of children who achieved pharmacokinetic targets after the first gentamicin dose was used as a measure of dosing guideline performance; the guideline achieved maximum concentration (Cmax) values below the target range (20–25mg/L) in 51% of patients. Ideal dosing guidelines were then developed using the mean dose required to achieved a Cmax of 23 mg/L for each patient. Univariate analysis or the Student t test was used to determine the existence of significant relationships between pharmacokinetic parameters and patient age and sex. The recursive binary partitioningmethod was used to determine critical values of age for dosage guideline development; analysis of variance was then used to compare the different levels obtained after use of this technique. Simulated administration of once-daily gentamicin in the following doses achieved a Cmax within or above target in 73% of patients: 1 year to 6 years, 10.5mg/kg/dose; girls ≥ 6 years, 9.5mg/kg/dose; and boys ≥ 6 years, 7.5mg/kg/dose. Doses were based on actual body weight for children who weighed less than 125% of ideal body weight or based on effective body weight for children 125%ormore of ideal body weight.

Conclusion. The initial gentamicin dosing guidelines were not effective in achieving Cmax. The new proposed dosing guidelines are predicted to achieve a Cmax within or above the target range in almost three quarters of patients. Subsequent dosing should be tailored according to plasma gentamicin concentrations.

Got Pharmacokinetics?

App Store, Kinetics, Pharmacy, RxCalc

RxCalc IconThe year is coming to an end, so why not celebrate by purchasing a copy of RxCalc for your iPhone? There’s still time to buy before the end of the year and at $0.99 it’s a real bargain! At least we think it is.

So, what do you get for less than a buck?

  • New Start – Vancomycin and Aminoglycoside.

  • Adjustment with Levels – Vancomycin and Aminoglycoside.

  • Ideal Body Weight

  • Creatinine Clearance (CG)

That’s just the 1.0 release. We have more features planned for the next release and we’d LOVE to hear from our users, just drop us an e-mail at support@applecorelabs.com, it’s that easy.

If you’d like more information on RxCalc, just visit the RxCalc product page. If you’d like to purchase RxCalc, visit the iPhone App Store.

Summary of Consensus Recommendations for Vancomycin Monitoring in Adults

Pharmacokinetics, Vancomycin

A recent article in November 2009 issue Pharmacotherapy summarizes the recommendations from the American Society of Health-System Pharmacists, the Infections Diseases Society of America, and the Society of Infectious Diseases Pharmacists on the monitoring of vancomycin in adults.

“The American Society of Health-System Pharmacists, the Infectious Diseases Society of America, and the Society of Infectious Diseases Pharmacists published a consensus statement on therapeutic monitoring of serum vancomycin levels in adults. These organizations established an expert panel to review the scientific data and controversies associated with vancomycin monitoring and to make recommendations based on the available evidence. As the members of this panel, we summarize the conclusions and highlight the recommendations from the consensus statement. We determined that the area under the concentration-time curve (AUC):minimum inhibitory concentration (MIC) ratio is the most useful pharmacodynamic parameter to predict vancomycin effectiveness and suggested a target ratio of 400 or greater to eradicate S. aureus. In addition, trough serum concentration monitoring is the most accurate and practical method to monitor vancomycin serum levels. Increasing trough concentrations to 15–20 mg/L to attain the target AUC:MIC ratio may be desirable but is currently not supported by clinical trials. Alternative therapies should be considered in patients with S. aureus infections that demonstrate a vancomycin MIC of 2 mg/L or greater because the target AUC:MIC ratio ( 400) is unlikely to be achieved in this setting. Increasing the dosage to result in higher trough concentrations may increase the potential for toxicity; however additional clinical experience is required to determine the extent.”

While the article contains nothing new in terms of vancomycin monitoring and kinetics, the recommendation to consider alternate therapy for S. aureus infections with an MIC >/= 2 mg/L is important to note.

The RxCalc Promotional has come to an end

Promotional, RxCalc

Our “FREE for the day” event has come to a close.

Thanks very much for downloading RxCalc, giving it a spin, and pushing it to the #12 spot in the Medical Apps Category!

Based on the success of this event we’re going to drop the price from $5.99 to $0.99!

I’d like to encourage those of you that took advantage of our little giveaway to please provide us with any feedback you may have, good or bad. We’re committed to improving RxCalc so your feedback is important to us. So, please, drop us a line at support@applecorelabs.com, or one of our other contact addresses, let us know how RxCalc is working for you, and thank you for your continued support.