PTCB Controlled Substances study guide

What this topic actually asks of you

Domain 2 of the PTCE is Federal Requirements, and it carries 18.75% of the exam — up from 12.5% in the 2020 outline (the 2026 outline keeps 18.75%). Two of its knowledge areas are the ones the exam labels calculation-based:

Federal requirements for controlled substance prescriptions (i.e., new, refill, transfer) and DEA controlled substance schedules

That is KA 2.2, and

Federal restricted drug programs and related medication-processing requirements (e.g., pseudoephedrine, Risk Evaluation and Mitigation Strategies [REMS])

That is KA 2.4. The third knowledge area, KA 2.3, is the operational side — receiving, storing, ordering, labeling, dispensing, returning, take-back programs for, loss or theft of, and destroying controlled substances. Together the three are everything a pharmacy does with a controlled substance except the clinical judgment — which schedule a drug sits on, how a controlled prescription is written and filled, how the drugs are ordered and counted, and what happens when some of them go missing.

The whole topic turns on one idea: the schedule sets the rules. A technician who knows a drug is a Schedule II knows there are no refills, that the order form is different, and that the count is exact. The schedule is not a trivia label; it is the switch that selects which of five sets of rules applies. Learn the switch and the rules follow.

The federal frame is the exam's frame. The PTCE tests federal law. A state may be stricter — shorter fill windows, tighter ratios, extra reporting — and where it is, the stricter rule governs what you actually do. But a question that asks what the federal rule is wants the federal number, and this guide teaches the federal number and says so where a state may differ.

The one arithmetic fact is the DEA number. A registration number has a check digit, and a technician can validate one by hand. That is the only calculation in this topic, and it is worth learning properly because it is the cleanest "is this prescription forged?" test the counter has.

The controlled-substance schedules

The five schedules, defined

The Controlled Substances Act sorts every controlled drug into one of five schedules. The sort is set by three questions — how much potential for abuse, whether the drug has a currently accepted medical use in the United States, and how far use leads to dependence (21 U.S.C. 812; the lists themselves are at 21 CFR 1308.11–1308.15).

The definitional trap is Schedule I. It is the schedule where the drug has no currently accepted medical use in treatment in the United States and lacks accepted safety for use under medical supervision. A drug can have a real medical use elsewhere in the world and still be Schedule I here; the schedule follows the federal finding, not the pharmacology.

The drugs the exam names

The exam tests the drugs that sit on each schedule. These are the ones to know cold, checked against the DEA's schedule lists (21 CFR 1308.11–1308.15):

• Schedule I — heroin, LSD, marijuana (federally, except as noted below), MDMA (ecstasy), psilocybin, peyote. None is prescribable.
• Schedule II — the strong opioids and the stimulants: oxycodone, hydrocodone combination products, morphine, methadone, fentanyl, hydromorphone, oxymorphone, meperidine; amphetamine, dextroamphetamine, lisdexamfetamine, methylphenidate; and cocaine (Schedule II; it has a limited medical use as a topical anesthetic). Hydrocodone combination products were moved from Schedule III to Schedule II on October 6, 2014 — before that date the same bottle was a C-III, which is why a question can turn on the date.
• Schedule III — anabolic steroids and testosterone; ketamine; buprenorphine (including the buprenorphine/naloxone combination products); codeine combination products containing not more than 90 mg of codeine per dosage unit (the acetaminophen-and-codeine tablets); dronabinol capsules (the synthetic THC product — the oral solution, Syndros, is Schedule II). Also the appetite suppressants benzphetamine and phendimetrazine.
• Schedule IV — the benzodiazepines (alprazolam, diazepam, lorazepam, clonazepam, chlordiazepoxide); the "Z-drug" hypnotics (zolpidem, zaleplon, eszopiclone); tramadol; carisoprodol; phenobarbital; modafinil; and the mixed agonist-antagonist opioids (pentazocine and butorphanol). (Nalbuphine is not a controlled substance and does not belong on this list — a likely distractor.)
• Schedule V — the cough preparations containing not more than 200 mg of codeine per 100 mL or per 100 g; diphenoxylate with atropine (Lomotil); pregabalin; and lacosamide.

Two codeine facts decide a whole family of questions. A codeine combination product is Schedule III when it holds not more than 90 mg of codeine per dosage unit; a cough syrup is Schedule V when it holds not more than 200 mg of codeine per 100 mL or 100 g. The strength is the switch — the same drug crosses a schedule line on quantity alone.

The status of marijuana is genuinely in motion, and the statement below is the one to hold. In general marijuana remains Schedule I. A DEA final rule published in April 2026 (91 FR 22714) moved marijuana in FDA-approved drug products and marijuana held under a state medical-marijuana license to Schedule III; all other marijuana stays Schedule I, and the broader rescheduling question went to a DEA hearing and is still pending. Because the status is live, no bank item in this course keys a marijuana schedule — but the guide states where it stands, dated.

Who is registered, and the DEA number

Registration and the forms

Every pharmacy that dispenses controlled substances holds a DEA registration for each place it stores and dispenses them. The application is DEA Form 224 (a new registration); the renewal is DEA Form 224a. A registration for a pharmacy or practitioner runs for three years (21 CFR 1301.13). You may apply to reregister no more than 60 days before it expires, and the pharmacy may not dispense controlled substances until the registration is granted and the certificate issued.

Reading a DEA number

A registrant's DEA number is nine characters: two letters followed by seven digits.

• The first letter is the registrant type. An "A", "B" or "F" is a standard practitioner, hospital or pharmacy; an "M" is a mid-level practitioner (a nurse practitioner or physician assistant); a "G" is a government registrant (such as the Department of Defense); an "X" marked a DATA-waiver prescriber for buprenorphine. Since the MAT Act of 2023 eliminated the X-waiver, a new prescriber no longer needs one — an older "X" number is historical, and any practitioner whose DEA registration includes Schedule III may now prescribe buprenorphine within the ordinary rules.
• The second letter is the first letter of the registrant's last name. It ties the number to a person, which is why a prescription from "Dr. Alvarez" carrying a number whose second letter is "P" is worth a second look.
• The seven digits end in a check digit. That is the part a technician can verify.

Working the check digit

The check digit is arithmetic, and it catches a number that was invented or mistyped. The method is the one HL7 documents for the US DEA number as the national naming system for the identifier (DEA does not print it in the CFR; the algorithm has not changed in decades):

1. Take the seven digits.
2. Add the first, third and fifth digits together.
3. Add the second, fourth and sixth digits together, then multiply that sum by 2.
4. Add the two results. The last digit of that total is the check digit — which must be the seventh digit of the number.

Worked example one. The number BJ123456?.

• First, third and fifth digits: 1 + 3 + 5 = 9
• Second, fourth and sixth: 2 + 4 + 6 = 12, doubled = 24
• Total: 9 + 24 = 33 → the last digit is 3, so the number is BJ1234563.

Worked example two. Does MP4567814 check out?

• First, third and fifth: 4 + 6 + 8 = 18
• Second, fourth and sixth: 5 + 7 + 1 = 13, doubled = 26
• Total: 18 + 26 = 44 → the check digit is 4, and the number ends in 4, so it is valid.

Worked example three. A prescription carries AF8765432. Is it real?

• First, third and fifth: 8 + 6 + 4 = 18
• Second, fourth and sixth: 7 + 5 + 3 = 15, doubled = 30
• Total: 18 + 30 = 48 → the check digit must be 8, but the number ends in 2. The number is invalid — a red flag, not proof of forgery, but reason to verify the prescriber.

The check digit is a screen, not a verdict. A forged number can carry a correct check digit, and a valid number can still sit on a prescription for an illegitimate purpose. HL7 says the same thing in its own words: the check digit confirms the number's structure, not that the registration is active or that the prescriber may write what is on the paper. It is one test among many.

A controlled prescription that a pharmacist may fill

Purpose and corresponding responsibility

A controlled prescription is effective only if it is issued for a legitimate medical purpose by an individual practitioner acting in the usual course of professional practice (21 CFR 1306.04). The responsibility is first the prescriber's — but a corresponding responsibility rests with the pharmacist who fills it. An order that is not issued in the usual course of treatment "is not a prescription" at all, and the pharmacist who knowingly fills it is subject to the same penalties as the prescriber.

That is the legal shape of the most important idea in Domain 2: the pharmacy is not a vending machine that honors any paper with a valid DEA number on it. The corresponding responsibility is the pharmacist's — 1306.04 places it on the individual who fills the order. The technician's job sits upstream of it and is just as practical: at the first step, receiving the order, the technician is the one who can notice what does not fit — the date, the quantity, the dose, a second early fill — and flag it to the pharmacist. The judgment is the pharmacist's; catching the pattern that needs a second look is the technician's.

The required elements

Every controlled prescription must carry the elements at 21 CFR 1306.05:

• The date issued (and the prescription must be dated and signed on the day it is issued).
• The full name and address of the patient.
• The drug name, strength and dosage form.
• The quantity prescribed.
• The directions for use.
• The name, address and registration number of the practitioner, and the practitioner's signature (a manual signature in ink for a written prescription).

A paper prescription is signed the way a check is signed — "J.H. Smith" or "John H. Smith". A missing or altered element is the first thing to send back to the prescriber's office.

Red flags of a forged or altered prescription

Forgery is rarely a perfect imitation; it is a set of circumstances that do not fit. The DEA's Pharmacist's Manual and every board's guidance list the same red flags:

• The patient is not local — an out-of-town address, or a prescriber far from the patient.
• The drug does not fit the prescriber's practice — a painkiller from a dentist for weeks, a stimulant from a dermatologist.
• Cash payment or no insurance, especially with reluctance to use a plan.
• Quantity or directions that read altered — a "10" that was a "100", a strength written over.
• The patient is unusually anxious, unwilling to wait, or demanding a specific drug or quantity.
• The prescription is for a "cocktail" — a controlled opioid with a benzodiazepine and a muscle relaxant together.
• Repeated prescriptions for the same drug from different prescribers or at different pharmacies.
• A DEA number that fails the check digit, or does not match the prescriber's name.

None of these is proof. Each is a reason to slow down, confirm with the prescriber, and involve the pharmacist — never to guess.

Filling Schedule II

Ordering: Form 222 and CSOS

A Schedule II drug cannot be ordered on an ordinary invoice. It is ordered on a DEA Form 222 or through CSOS (the Controlled Substance Ordering System, an electronic equivalent under 21 CFR Part 1305). Since October 2019 the paper form is a single sheet, not the triplicate carbon form that older technicians remember.

The mechanics a question turns on (21 CFR 1305.11, 1305.13):

• The purchaser keeps a copy and sends the original to the supplier. The supplier records the containers shipped and the ship date on the original.
• An order may be filled in part, with the balance shipped within 60 days of the form's execution. No Form 222 is valid more than 60 days after the purchaser executes it.
• The purchaser records, on its own copy, the number of containers received and the dates they arrived — that is the receiving record.

Emergency oral prescriptions

In a genuine emergency, a pharmacist may dispense a Schedule II drug on a prescriber's oral authorization (21 CFR 1306.11(d)):

• The quantity is limited to what is adequate to treat the patient during the emergency period.
• The pharmacist immediately reduces the order to writing, with everything 1306.05 requires except the prescriber's signature.
• The prescriber must deliver a written (or electronic) prescription for the emergency quantity within 7 days, marked "Authorization for Emergency Dispensing" with the date of the oral order.
• If the written prescription does not arrive, the pharmacist must notify the DEA. Failing to notify voids the authority to have dispensed on the oral order.

Multiple prescriptions and the 90-day supply

A Schedule II prescription may not be refilled. But a prescriber may issue multiple prescriptions covering up to a 90-day supply, provided each is written for a legitimate purpose and each carries a written "do not fill before" date (other than the first, if it is to be filled immediately) (21 CFR 1306.12). This is not a refill; it is several prescriptions written at once. A pharmacy that fills them before the earliest fill date has violated the rule.

Partial fills

A Schedule II prescription may be filled in parts, and the time limits are a favorite exam target (21 CFR 1306.13):

• Because the pharmacy cannot supply the full quantity: the remainder may be filled within 72 hours of the first partial fill. If it is not, the pharmacist must notify the prescriber, and no more may be supplied without a new prescription.
• At the request of the patient or prescriber (a partial fill under CARA, 2016): the remaining portion must be filled not later than 30 days after the prescription was written (except an emergency oral prescription, which keeps the 72-hour rule).
• For a patient in a long-term care facility or with a documented terminal illness: the prescription may be filled in partial quantities, and no further partial fill may be made after 60 days from the issue date unless the medication is discontinued earlier. The rule words this as the prescription remaining valid for up to 60 days, but read it as a partial-fill window: the question it decides is how long a strip of partial fills may keep going, not whether the prescription is still "live" for a fresh full fill.

When a fax is the original

A fax normally only transmits a prescription, and the pharmacy still needs the original for a Schedule II. But in three cases the fax itself serves as the original (21 CFR 1306.11):

• A narcotic compounded for direct administration to a patient by parenteral, intravenous, intramuscular, subcutaneous or intraspinal infusion (home infusion) — 1306.11(e), Schedule II narcotics only.
• A prescription for a resident of a long-term care facility — 1306.11(f), which covers any Schedule II, not just narcotics.
• A narcotic prescribed for a hospice patient (the prescription is noted as hospice) — 1306.11(g), again narcotics only.

Filling Schedule III to V

Refills

A Schedule III or IV prescription may be filled or refilled no more than five times, and no later than six months after the date it was issued (21 CFR 1306.22). Both limits apply — a prescription with refills left but more than six months old is dead, and a six-month-old prescription with no refills used is also done. A prescriber may authorize refills orally, so long as the total stays within five refills and six months. A Schedule V prescription is refilled as authorized.

Transfers

Refill information for a Schedule III, IV or V prescription may be transferred between pharmacies one time only, unless the pharmacies share a real-time, online database, in which case up to the maximum allowed refills may be transferred (21 CFR 1306.25). The transfer is communicated directly between two licensed pharmacists; the transferring pharmacy marks the original "VOID" and records where it went, and the receiving pharmacy records that the prescription was transferred. A Schedule II prescription may not be refilled, so the one-time refill-transfer rule does not apply to it.

Transfers are not only about refills any more. Separate from the refill rule, a Schedule II–V electronic prescription may be transferred once, for its initial dispensing, between retail pharmacies, at the patient's request (21 CFR 1306.08(e), the 2023 e-prescribing rule). So the old blanket "a C-II can never be transferred" is wrong: a C-II refill cannot exist, but an electronic C-II can move to another pharmacy once before it is ever filled, and any authorized C-III–V refills travel with it. The two rules answer two different questions — can this unfilled prescription be sent to us? (once, 1306.08(e)) and can we take over its refills? (once without a shared database, 1306.25).

Schedule V without a prescription

A controlled substance that is not itself a prescription drug — the classic is a small-codeine cough syrup — may be sold without a prescription under 21 CFR 1306.26, on conditions designed to keep it accountable:

• The sale is made by a pharmacist (a technician may complete the cash or delivery only after the pharmacist has met the professional and legal duties).
• No more than 240 cc (8 ounces) of an opium-containing product, or 120 cc (4 ounces) of any other such product, to the same purchaser in any 48-hour period — and no more than 48 dosage units of an opium-containing product or 24 dosage units of any other, per 48 hours.
• The purchaser is at least 18 years old and, if not known to the pharmacist, furnishes suitable identification (including proof of age).
• The pharmacist keeps a bound record book with the name and address of the purchaser, the name and quantity of the drug, the date, and the dispensing pharmacist — kept under the usual recordkeeping rule.

These products are what the exam calls "exempt narcotics." The word exempt means exempt from the prescription requirement — not exempt from the record, the age check, or the quantity limit.

Inventory, records and accountability

The inventory

Every registrant takes an initial inventory when it first handles controlled substances, then a biennial inventory — at least every two years (21 CFR 1304.11). Two counting rules follow the schedule:

• Schedule II is counted exactly. No estimating.
• Schedule III, IV and V may be estimated, unless the container holds more than 1,000 tablets or capsules, in which case it is counted exactly.

An inventory is taken as of the opening of business or the close of business on the inventory date, and it says which. When a drug is newly scheduled, every registrant takes an inventory of it on the effective date of the scheduling rule.

Retention

Controlled-substance records — inventories, order forms, invoices, the bound book — are kept for two years (21 CFR 1304.04). Schedule II records are kept separate, and the Schedule III–V records must be readily retrievable.

Storage and access

Federal rules ask for one of two arrangements (21 CFR 1301.75(b)): a securely locked, substantially constructed cabinet, or dispersal of the controlled stock through the noncontrolled stock so that theft and diversion are obstructed. Either satisfies the rule; the question is whether the arrangement obstructs access, not whether a lock is in sight. Open shelving beside the noncontrolled stock, a box at the register and the refrigerator are none of the two.

Access is not the technician's call. A cabinet found unlocked at the end of the day is reported to the pharmacist — what was reachable while it stood open is a possible loss, and a quietly relocked cabinet hides that from the record the biennial inventory and a Form 106 depend on.

Theft, loss, disposal and returns

• Theft or significant loss: the registrant notifies the DEA Field Division in writing within one business day of discovering the loss or theft, and then files DEA Form 106 through the DEA's secure network within 45 days (21 CFR 1301.76). Whether a loss is "significant" is judged case by case — the quantity, the drug, whether a pattern is visible, and what the local diversion picture looks like.
• Disposal by the registrant: a registrant destroys controlled substances under the Part 1317 rules, documenting the destruction on a DEA Form 41 (the registrant's record of controlled substances destroyed). Product may also go to a reverse distributor — a DEA-registered firm that takes expired, damaged and unusable controlled stock, manages the credit and the destruction, and issues a receipt the pharmacy keeps as its record.
• Patient take-back: a pharmacy that wants to host a collection receptacle or a mail-back program registers as a collector with the DEA under Part 1317. The pharmacy does not "take back" controlled substances informally; the collection is a registered activity with its own handling.
• Returning stock to a supplier: a pharmacy may return unopened, unexpired stock to the supplier it obtained it from. A Schedule I or II return moves on a Form 222 or CSOS; for the lower schedules (III–V), a written record (the invoice) follows the shipment. What may not happen is a return that puts any controlled substance back into the supply chain once it has left the pharmacy's control toward a patient.
• The 5% rule (21 CFR 1307.11): a practitioner may distribute — without registering as a distributor — an amount of controlled substances to another practitioner that does not exceed 5% of the total dosage units of all controlled substances distributed and dispensed in a calendar year. Above 5%, a distributor registration is required.

The federal numbers, in one table

Each row cites the section it comes from. This is the table to memorize before the exam.

Pairs to keep apart

Every substitution below is a distractor waiting to be written.

How to practice this

• Read the free controlled-substances practice set and, on each item, name the schedule first — the schedule usually picks the answer before you reach the choices.
• Recompute one DEA check digit from memory each session: odd positions plus twice the even positions; the units digit is the check. It is the only arithmetic here, and it is free marks.
• Write the fill limits on one line: C-II: no refills, 90-day multiples, 72 h / 30 days / 60 days partials, 7-day emergency, fax for LTCF/hospice/home infusion. If you can say that line, most of the C-II items answer themselves.
• Drill the pairs above as flashcards, front to back and then back to front.
• Work the federal programs, waste, recalls and DSCSA guide next — it is the other half of Domain 2 — and the pharmacy calculations guide if the check-digit arithmetic is what keeps going wrong.

Where to go next

• Next topic — federal programs, waste, recalls and DSCSA
• The exam itself — the passing score, how many questions, and what makes the PTCB exam hard.

This topic sits inside Domain 2 — Federal Requirements, 18.75% of the exam — the outline's own weight, and PTCB publishes no per-knowledge-area split.

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