Below are several rough sketches made during our second meeting on the 18th as we developed an initial design and went through several options, discussing the advantages and potential problems of each.
This is the very first sketch we made as we talked about using a bottle-shaped design with a user interface on the side and an inhaler mouthpiece coming out of one end. Obviously, the initial diagram is an extremely rough sketch made in an attempt to give all team members a rough visual image of our final product and to get the team on the same page. Drawings easily allowed us to convey what we are imagining in our minds when it may be difficult to describe these designs in words.
These drawings were made as we attempted to work out the connection between the bag holding the medication, the inhaler, and the mouthpiece for patient use. The sketches show inside views of the device. We considered a removable cap over the mouthpiece as well as both a sliding mouthpiece that can be pulled out of the device and a mouthpiece that can be snapped up perpendicular to its storage position. Some concerns we ran into included replacement/refilling of the medication bag and the level of sanitation of the mouthpiece.
Following our initial rough sketch, this is a more detailed drawing of our very first design - a very large, bulky, and shoe box-like container with a mouthpiece that can flip out on the side next to a user interface. The top portion shows a top-view of the bag of medication.
Here is a more sketch we made as we discussed the mechanics behind the medication bag - how it is initially installed, how it can then be replaced/refilled (most likely by a doctor/pharmacist), and how specifically it releases a set amount of medication to be administered to a patient.
Here is a rough sketch of a more realistic model of our first design. We estimated the size to be approximately similar to a bottle 10 in. long by 3 in. wide. The user interface is placed at one end by the mouthpiece under a removable cap, and the bag of medication is stored at the other end.
At today's recitation meeting, we began the final drawing of our product on the computer and compiled several diagrams. Below is a diagram of design decisions we have made, progressing from our conceptual to detailed designs and finally to our two rival designs.
At our third meeting during recitation, we discussed the pros and cons of various possible inhaler designs to ensure that the MDI-based "mistifyer" design we settled on is the best decision. We focused specifically on the administration of the different types of medication by each device and the mechanics behind the drug delivery.
Designs administering powdered medication:
Pros:
can be used for medication available in solid/powdered form
larger variety of medications available in this form/to be administered by these devices
Cons:
hard to have a reasonably compact drug reservoir with at least 200 doses
powered mechanically (such as external force provided by twisting canister, rather than pressurized liquid/gas)
mechanical power allows for greater control
can be used for normal liquid medications
safer
easier to store (not pressurized)
Cons:
requires mechanical power for drug delivery (possibly not as easy to use by children/elderly)
By next week, we hope to have the estimated weight, size, and cost of our final product. The components of our design so far are similar to the total combination of the following items:
mouthpiece (inhaler)
reservoir (like a bottle)
computer/user interface (like a graphing calculator)
Our second meeting took place the night of Wednesday the 18th. We sat to discuss what we had each compiled so far and to come to several conclusions. Below are some notes of what was discussed during the meeting. Following is a preliminary list of detailed specs.
·MDI idea
·200-dose capacity, large capacity
·how to change medication: bag, more hygienic/sterile
ovacuumed liquid in bag, 2 jets of water collide à mist
§bag constricts around liquid as it is used up
§safer than using CFCs
opowered by mechanical energy from spring twisted by patient?
Anyone who can use an inhaler (children, adults, elderly)
Must have the physical capabilities to coordinate the user interface (read/respond to the screen, press buttons) and to learn how and when to breathe in at the right time in order to receive a dose
Ages six and up (unless otherwise authorized by a doctor)
Exceptions: if too old to take a deep breath, etc.
Functions/Performance
Similar to MDI
Mist of medication inhaled into the lungs
Absorption of medication via alveoli
Medication stored in liquid form in a vacuumed bag
Roughly 100mL needed for the specified 200 doses (variable depending on the medication and dosage)
Any medication that can be prescribed as a mist/aerosol works
Butorphanol (analgesic)
Inhaler mouthpiece + iPod touch + water bottle (size of bottle depends on medication used and dosage)
Screen + buttons = iPod touch
User interface acts as control of dosage by patient/doctor
Performance
Medication administered as a mist
Two jets of liquid colliding to form a mist
Battery powered; rechargeable
Ease of Use/Size/Weight
Weight of above 3 items
Roughly 10 inches x 2.5 inches x 2.5 inches
Portable: use anywhere; can be carried in a purse/bag
Maintenance/Repair/Reliability/Safety
Time interval of dosage determined by doctor specific to each patient
User interface locks dosages
One dose every set number of hours
Displays Yes/No to patient attempting to overdose
Lifetime
Bag of liquid medication needs regular replacement
Mouthpiece regularly cleaned
At the end of the meeting, we divided up further research for the following week:
David:user interface, mechanism of drug delivery
Julie:drugs (what can be delivered as a mist, dosage in mist), absorption through lungs, how effective
Connie: blogs, both David and Julie's areas of research
All three members will also try to think of a company name throughout the next few weeks. Several diagrams of various models/user interfaces were sketched through our discussions during the meeting (beginning with a large boxy device and advancing to smaller, more compact designs). These drawings will be scanned and posted in following posts.
Following this first meeting during recitation, the three of us individually did research on our assigned portions and e-mailed any information gathered to the rest of the group. We looked over each other's research to prepare for our meeting the next day, Wednesday the 18th, following the Math 114 midterm. This is what we each came up with.
Julie:
Potential medications (analgesics) – given “by the clock” every 3 to 6 hours
Morphine
Pure pharmaceutical morphine powder exists
Interacts with opioid receptors in nervous system
Agonist opioid – binds to receptor and triggers response by cell
High-affinity binding to the muu-opioid receptor
Second strongest pain killer; natural opiate
Oxycodone
Semi-synthetic opiate
Fever negative side effects when patients switch from morphine
Reduce pain in 10 to 15 minutes
Oxycodone à alpha and beta oxycodol à oxymorphone à alpha and beta oxymorphol à norooxymorphone à norooxycodone à alpha and beta noroxycodol and noroxymorphone
Vulnerable to drug interaction (metabolized by CYP P450 in liver)
Metered-dose Inhaler (MDI)
Absorption in the alveoli of lungs into bloodstream
“Inhalers are being developed and tested to deliver fast-acting morphine for breakthrough pain at rates that are just as fast as any direct intravenous shot can deliver.”
Medication usually a suspension
Need to be shaken vigorously
In a little container which gets changed for a new one into inhaler
Dry Powder Inhaler (DPI)
Powder-form medication
Counter on DPI referring to dosages left
Potential for revamping that for our user interface
(ADVAIR) Diskus (see figure 1)
“The smallest dosage is 100mcg/50mcg, the intermediate dosage is 250mcg/50mcg and the highest dosage is 500mcg/50mcg (mcg refers to micrograms)”
More expensive than MDI
Other possibilities
Quick-dissolving wafers
Dissolve very quickly through the tongue, no water needed
-Butorphanol: Pain relievers can be successfully administered through aerosols. ‘Opiods: Other routes for use in recovery room’ said that when butorphanol (a pain reliever) was administered orally, peak blood levels of the drug were reached after about 30 min of administration)
-The butorphanol was administered nasally in doses of .25 mL of butorphanol solution. From this, I calculated that for 200 doses of oral administration of this particular drug, we’d need a 50 mL drug reservoir in our PCA device.
-Aerosol Drug Delivery:Another article (Bioengineering of Therapeutic Aerosols) talked about delivery of drugs via aerosols.
-The main emphasis was on insulin aerosols, but the application for pain relief was mentioned
-The article also mentioned that smaller particles are absorbed through the alveoli better. Because insulin is a hormone (big protein molecule) and butorphanol (one pain relieving drug) is a smaller molecule, I think its possible to deliver pain relief through the lungs.
-The Respimat Soft Mist Inhaler: -This inhaler looked like a good design for our project, because it turns an unpressurized liquid (with the drug in solution or suspension) into a mist, through the collision of two streams of liquid.
-Other inhalers require the use of a pressurized liquid, a volatile (easy to evaporate liquid), or nebulizer (pressurized gas)
-The mist produced is supposedly easier to breath in than other mists
-Design Specifications: I arrived at these preliminary design specifications based on research on other Patient Controlled Analgesics (particularly the Smith’s Medical CADD-Solis from lecture), the volume of 200 doses of buterphanol, and our design ideas
-2 in. by 2 in. screen
-about 1.5 pound weight
-about 100 L liquid drug reservoir
-attached inhaler device (inhalers, like the Respimat Soft Mist Inhaler, are pocket-size and light weight. They can be attached by a tube to the main reservoir and computer unit)
-able to fit in a small bag and be carried around.
-Nasal Pain Relief: Articles I read from PubMed were talking about pain relievers delivered by a nasal spray. This doesn’t really fit in with Dr. Bogen’s guidelines, but I got some good information from one article (Opiods: Other routes for use in recovery room)
Sources:
Opiods: Other routes for use in recovery room. Asenjo JF, Brecht KM. Current Drug Targets, 2005
A review of the development of Respimat® Soft MistTM Inhaler R. Dalbya, M. Spallekb, T. Voshaarc
BIOENGINEERING OF THERAPEUTIC AEROSOLS
David A. Edwards and Craig Dunbar
Connie:
CADD-Solis Ambulatory Infusion System
·Useful features
oAmbulatory – allows patient mobility with device, compact, lightweight
oLights to allow visual monitoring of status of pump (if medication is being delivered or not, if a new dose is available for delivery (when required amount of time has passed since last delivery))
oRecords of drug dosage – graphs and trend reports for patient management (by patients themselves or by doctor/caretaker?)
oSoft key interface (soft buttons) for easy navigation
oMedication lockin for safety and security (“cassette reservoirs”)
oAlarm system – different colors/sounds for different warnings
§For our product, warnings of overdose/attempts to take too many doses in too short a time?
oKeypad lock – unlock with fingerprint? For added security so children can not fool around with the device
§Device for children – fingerprint unlock too complicated? Sometimes difficult (even on laptops) to position fingers correctly; possibly allow to register more than one set of fingerprints (parent/adult to help children use device)
oDrug concentration/measurements to eliminate errors (clear display of amount of drug being delivered, clear units)
oLatch to attach cassette (in our case, latch to attach user interface to medication/inhaler?)
oScrolling to prevent double key press errors (clear button to push when selecting delivery of medication, maybe add a confirm key?)
·Specs
oPump size 1.6 in. x 4 in. x 5 in. pump alone
oScreen size 2.12 in. x 2.12 in. (320 pixels x 320 pixels)
o21 oz. including 4 AA alkaline batteries
§Battery power – 4 AA batteries, AC adapter, rechargeable battery pack
·Essential not to run out of batteries during a crucial moment (backup batteries, normally run on charged battery)
·Battery life 120 hours at 10 mL/hr
oCassette and keypad lock with three security access levels: keypad (patient), clinician code, administrator code
§For our device, use fingerprints/can store multiple sets of fingerprints? Doctor, patient, parent/caretaker (such as if patient is a child or elder)
oUnits of delivery: 0 to 9999 mL programmable in 1 mL increments, displayed in 0.1 mL increments; can deliver in mL, mg, mcg (micrograms)
oConcentration:
§0.1 to 0.5 mg/mL in 0.1 mg/mL increments
§0.5 to 1 mg/mL in 0.5 mg/mL increments
§1 to 15 mg/mL in 1 mg/mL increments
§15 to 100 mg/mL in 5 mg/mL increments
§1 to 15 mcg/mL in 1 mcg/mL increments
§15 to 100 mcg/mL in 5 mcg/mL increments
§100 to 500 mcg/mL in 100 mcg/m increments
oDose lockout
§1 minute to 24 hours (programmable by doctor?)
·1 minute for values between 1 and 20 minutes
·5 minutes for values between 20 minutes and 24 hours
§Max doses 1 to 60 per hour (programmable by doctor)
o0.1 to 1000 mL (or mg or mcg equivalent) delivery limit amount
oMoisture protection – splash proof
oLogs 5000 events
oTurn on or off, can set alarms, alarm volume, alarm sound theme
oDose graph, delivery history, pie chart
§Dose counter, delivery log, event log
oBacklight display with AC power, indicator lights
Metered-dose Inhaler (MDI) vs. Dry Powder Inhaler (DPI)
·Both can be used for children older than 5
·If a child can suck on a straw, can inhale from a DPI or MDI with valve holding chamber
·Both handheld, portable
·MDI
orequires inspiratory effort
o10-25% of drugs deposited in lung, 60-70% in mouth/throat
oWhen used with holding chamber, 25-30% deposited in lung, 4-10% in holding chamber
oMedication in aerosol form, pressurized canister inside plastic case with mouthpiece
oUses chemical propellant to push medication out of inhaler (commonly CFCs and HFCs, mostly HFCs now since CFCs cause damage to ozone layer)
oHarder to keep track of number of deliveries left – can check total number of puffs contained, keep track of how many times used
oSome MDIs count puffs each time inhaler pressed
oUses a spacer – tube attached that holds medication until patient can breathe it in
oEnsures that anyone that may not use the device correctly gets medication to their lungs, lessens side effects; helps patient with difficulty coordinating breathing with inhaler
·DPI
o6-32% deposited in lungs (depending on device), 60-70% in mouth/throat
oOnly DPI approved for child use is budesonide inhalation powder (for wheezing/asthma)
oMedication in form of dry powder
oDelivers medication to drugs as patient inhales through device
oDoes not contain propellants or other ingredients – only medication
