4 • interpretat on of Prescr pt ons and Med cat on Orders 67
Medication Scheduling, Medication Adherence, and Medication
68 Pharma u al c al ula on
(2)
How many milliliters o medicine should be dispensed?
Answer: 5 mL times 4 (doses per day) equals 20 mL times 10 (days) equals 200 mL.
A pharmacist may calculate a patient’s percent compliance rate as follows:
% Compliance rate N mber of days supply of medication N umber of days
= u
ssince last Rx refill ×100
(3) W hat is the percent compliance rate i a patient received a 30-day supply o medicine and returned in 45 days or a ref ll?
% Compliance rate days .
= 30 days × =
45 100 6 %6 6
In determining the patient’s actual (rather than apparent) compliance rate, it is impor- tant to determine if the patient had available and used extra days’ dosage from some previ- ous filling of the prescription.
Medication disposal is an important consideration for safety and environmental con- cerns. Medications that are no longer used or out of date may be disposed of by the following methods: (a) “take back” programs for disposal by pharmacies; (b) mixing medications with kitty litter, coffee grounds, or other such materials and disposing along with household trash;
and (c) flushing medications down the drain for specific drugs as approved by the FDA.14
c a SE In POIn T 4 .2 A 72 -y ar-old mal who d a adm d o h m r- g n y room w h hor n of r a h and g n ral w akn . t r al an m a, hypo n on, a r al f r lla on, and oronary ar ry lo kag . Dur ng 2 w k of ho - p al za on, h pa n r n ra nou nfu on , oral m d a on , and lood ran fu on ; four ard o a ular n ar n r d; and h pa n d harg d w h h follow ng pr r p on :
c lop dogr l ulfa (PLAviX) a l , 75 mg, 1 a q.d.
P ogl azon hydro hlor d (Ac t Os ) a l , 15 mg, 1 a q.d.
Pan oprazol od um (PROt ONiX) a l , 40 mg, 1 a . .d.
s m a a n (ZOc OR) a l 4 0 mg, 1 a q.d. h. .
HUMULiN 70/30, nj 35 un q.d. am and 45 un q.d. pm
c ar d lol (c ORe G) a l , 3.125 mg 1 a . .d. × 2 wk; h n 6.25 mg 1 a . .d.
Am odaron hydro hlor d (c ORDARONe ) a l , 200 mg, 2 a . .d. × 7 d; h n 1 a . .d. × 7 d; h n 1 a q.d.
Dulox n hydro hlor d (c YMb ALt A) ap ul , 30 mg, 1 ap q.d. × 7 d;
h n 1 ap . .d.
(a) How many o al a l and ap ul would h pa n n ally ak ng da ly?
( ) if HUMULiN on a n 100 un p r m ll l r, how many m ll l r would adm n r d a h morn ng and a h n ng?
( ) How many c ORDARONe a l would on u a 30-day upply?
(d) if 60 c YMb ALt A ap ul w r n ally d p n d and h pa n r qu d a r f ll af r 17 day , medication nonadherence and hu h pa n ’ w ll- ng a r a ona l on rn? s how al ula on .
Penicillin V Potassium O ral Solution 125 mg/5 mL
D isp. mL
Sig. 5 mL q 6 h AT C × 10 d
4 • interpretat on of Prescr pt ons and Med cat on Orders 69
PRa c TIc E PROb l EMS
Authors’ N ote: some abbreviations used in these practice problems may appear only infre- quently in practice and are included here for instructional purposes.
1. Interpret each of the following Subscriptions (directions to the pharmacist) taken from prescriptions:
(a) Disp. supp. rect. no. xii
(b) M. ft. iso. sol. D isp. 120 mL (c) M. et div. in pulv. no. xl
(d) DT D vi. N on rep.
(e) M. et ft. ung. Disp. 10 g (f) M. et ft. caps. D T D xlviii
(g) M. et ft. susp. 1 g/tbsp. Disp. 60 mL (h) Ft. cap. #1. D T D no.xxxvi N .R.
(i) M. et ft. pulv. D T D #C (j) M. et ft. I.V. inj.
(k) Label: hydrocortisone, 20 mg tabs
2. Interpret each of the following Signas (directions to the patient) taken from prescriptions:
(a) Gtt. ii each eye q. 4 h. p.r.n. pain.
(b) T bsp. i in ⅓ gl. aq. q. 6 h (c) Appl. am & pm for pain prn.
(d) Gtt. iv right ear m. & n.
(e) Tsp. i ex aq. q. 4 or 5 h. p.r.n. pain (f) Appl. ung. left eye ad lib.
(g) Caps i c aq. h.s. N .R.
(h) Gtt. v each ear 3 × d. s.o.s.
(i) Tab. i sublingually, rep. p.r.n.
(j) Instill gtt. ii each eye of neonate
(k) Dil. c = vol. aq. and use as gargle q. 5 h
(l) Cap. ii 1 h. prior to departure, then cap. i after 12 h (m) Tab i p.r.n. SOB
(n) Tab i qAM H BP
(o) Tab ii q 6 h AT C UT I (p) 3ii 4 × d p.c. & h.s.
(q) ss a.c. t.i.d.
(r) Add crushed tablet to pet’s food s.i.d.
3. Interpret each of the following taken from medication orders:
(a) AMBIEN 10 mg p.o. qhs × 5 d
(b) 1000 mL D 5W q. 8 h. IV c 20 mEq KC1 to every third bottle (c) Admin. prochlorperazine 10 mg IM q. 3 h. prn N &V
(d) Minocycline H Cl susp. 1 tsp p.o. q.i.d. D C after 5 d (e) Propranolol H Cl 10 mg p.o. t.i.d. a.c. & h.s.
(f) N PH U-100 insulin 40 units subc every day am (g) Cefamandole nafate 250 mg IM q12h
(h) Potassium chloride 15 mEq p.o. b.i.d. p.c.
(i) Vincristine sulfate 1 mg/m2 pt. BSA (j) Flurazepam 30 mg at H S prn sleep (k) D5W + 20 mEq KCl/L at 84 mL/h
(l) 2.5 g/kg/day amino acids T PN
(m) Epoetin alfa (PRO CRIT ) stat. 150 units/kg subQ . 3 × wk. × 3–4 wks
70 Pharma euti al c al ulations
(n) MT X 2.5 mg tab t.i.d. 1 ×/wk (o) H CT Z tabs 12.5 mg q.d. am
4. (a) I a 10-mL vial o insulin contains 100 units o insulin per milliliter, and a patient is to administer 20 units daily, how many days will the product last the patient?
(b) I the patient returned to the pharmacy in exactly 7 weeks or another vial o insulin, was the patient compliant as indicated by the percent compliance rate?
5. A prescription is to be taken as ollows: 1 tablet q.i.d. the irst day; 1 tablet t.i.d.
the second day; 1 tablet b.i.d. × 5 d; and 1 tablet q.d. therea ter. H ow many tablets should be dispensed to equal a 30-day supply?
6. In preparing the prescription in Figure 4.3, the pharmacist calculated and labeled the dose as “1 teaspoon ul every 12 hours.” Is this correct or in error?
7. Re er to Figure 4.1 and identi y any errors or omissions in the ollowing prescrip- tion label:
Patient: Mary Smith Dr. JM Brown Date: Jan 9, 20yy
Take 1 capsule every day in the morning Ref lls: 5
8. Re er to Figure 4.4A and identi y any errors or omissions in the ollowing pre- scription label:
Patient: Brad Smith Dr. JM Brown Date: Jan 9, 20yy
Take two (2) teaspoon uls every twelve (12) hours until all o the medicine is gone
Amoxicillin 250 mL/5 mL Ref lls: 0
9. Re er to Figure 4.5 and identi y any errors or omissions in the ollowing prescrip- tion label:
Patient: Brad Smith Dr. JM Brown Date: Jan 9, 20yy
N asal spray or chemotherapy-induced emesis. U se as directed.
Discard a ter 60 days.
Metoclopramide H Cl 10 g/100 mL N asal Spray Ref lls: 0
10. Re er to Figure 4.2 and identi y any errors or omissions in a transcribed order or the irst three drugs in the medication order:
(a) Propranolol, 40 mg orally every day (b) Flutamide, 20 mg orally every morning
(c) Flurazepam, 30 mg at bedtime as needed or sleep
11. Re er to Figure 4.6 and identi y any errors in the ollowing prescription label:
Patient: Mary Jones Dr. JM Brown Date: Oct 20, 20yy
Swallow one (1) capsule at bedtime.
Gabapentin 100 mg
10 g/100 mL N asal Spray
Rx: 9876543 Ref lls: 6
4 • interpretat on of Prescr pt ons and Med cat on Orders 71
c a l c q UIz
4.A. Interpret the underlined portions taken directly from current product references15: (a) Dose of ritonavir when coadministered with fluconazole: 200 mg q6h × 4d (b) Dose of epoetin alpha: 150 units/kg SC TIW
(c) Dose of acetylcysteine: for patients >20 to <40 kg, 150 mg/kg
(d) Pediatric dose of cefuroxime axetil: 30 mg/kg/day, divided dose (b.i.d.)
(e) Dose of ciprofloxacin hydrochloride: 750 mg tablet q12h or 400 mg IV q8h (f) Dose of interferon alpha-2b: 30 MIU/m2 TIW
(g) Infusion rate, rocuronium bromide: 4 mg/kg/min
(h) Dose of enoxaparin sodium injection: 1.5 mg/kg q.d. SC (i) Dose of voriconazole: 200 mg po q12h × 8 d
(j) Dose of certolizumab pegol: 200 mg + MTX q2 wk
4.B. The following are hospital medication orders and, in parenthesis, the product avail- able in the pharmacy:
(a) Furosemide 40 mg IV qd (10 mg/mL in 2-mL syringes) (b) Erythromycin 750 mg IV q6h (500 mg/vial)
(c) Acyclovir 350 mg IV q8h (500 mg/vial)
(d) MEGACE 40 mg PO tid (40 mg/mL oral suspension) (e) FORTAZ 2 g IV q8h (500 mg/vial)
For each, indicate the quantity to be provided daily by the pharmacy.
12. In a clinical study of drug–drug interactions, the following drugs were coadministered:
Ritonavir: 600 mg b.i.d. p.o. × 7 d T heophylline: 3 mg/kg q8h × 7 d Translate the directions
13. Translate “10 mIU/mL.”
14. T he package insert for interferon alpha-2b states the dose based on body surface area (BSA) for the treatment of hepatitis B as 3 M IU/m2 TIW for the first week of therapy followed by dose escalation to 6 M IU/m2 TIW (maximum of 10 MIU/m2 TIW ) administered subcutaneously for a total duration of 16 to 24 weeks. Translate the por- tion which states “6 M IU/m2 T IW.”
15. Translate “simvastatin 20 mg q.p.m.”
16. Interpret the following from the literature: “lopinavir/ritonavir 400 mg/100 mg b.i.d + efavirenz 600 mg q.d.”
17. Using the information in Figure 4.5, calculate (a) the number of milligrams of metoclopramide H Cl in each milliliter of the prescription and (b) the number of milliliters of nasal spray that would provide a patient with an 80-mg dose of metoclopramide H Cl.
18. If, in the above problem, each nasal spray actuation delivered 0.4 mL, how many full days would the prescription last if the patient administered the stated dose three times daily?
72 Pharma euti al c al ulations
a n SWERS TO “c a SE In POIn T” a n d PRa c TIc E PROb l EMS Case in Point 4.1
(a) Since aa. means “of each,” 10 mg lisinopril and 10 mg hydrochlorothiazide are needed for each capsule. And since D .T.D . means “give of such doses,” 30 cap- sules are to be prepared. T hus,
10 mg lisinopril × 30 (capsules) = 300 mg lisinopril and
10 mg hydrochlorothiazide × 30 (capsules) = 300 mg hydrochlorothiazide are needed to fill the prescription.
(b) Since q.s. ad means “a sufficient quantity to make,” the total in each capsule is 300 mg. T he amount of lactose per capsule would equal 300 mg less the quantity of the other ingredients (10 mg + 10 mg + 40 mg), or 240 mg. T hus,
240 mg lactose/capsule × 30 (capsules) = 7200 mg = 7.2 g lactose.
(c) Take one (1) capsule in the morning before breakfast.